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Bowers & Wilkins 705 S2s with Audiolab Monoblocks and a Walkman?

To Diego Estan,

Hope all is well. My name is John, from Hong Kong.

Recently I decided to update my hi-fi system. I am no audiophile or sound engineer, and have little to no understanding of audio jargon! I read and re-read it, trying to figure out what would suit me best, but I get lost in a maze of opinions.

Anyhow, I’m thinking of Bowers & Wilkins 705 S2 speakers with Audiolab 8300MB monoblock amplifiers, using my Sony Walkman NW-ZX507 digital audio player as a source. The room is small (very similar to your room dimensions). All my music files are MP3 and are of lesser quality than they should be.

I picked the speakers based on the endless praise I’ve read regarding their distinctive midrange and highs without sacrificing bass. For the monoblocks, I chose them purely for their looks; clean and minimalistic.

I’ll hook up the Walkman to the monoblocks with XLR cables.

Does that make sense? Your input is highly appreciated. Thank you, and be safe.


Hong Kong

First, you mentioned MP3 files. When encoded at the highest bit rates (256 or 320kbps), MP3s can sound very good, and in many cases be nearly sonically indistinguishable from CD quality. However, given how much money you’re willing to spend on this system I would urge you to experiment with lossless file formats such as FLAC, ALAC, or WAV. Try ripping CDs to FLAC, or subscribing to a streaming service that offers CD quality (16-bit/44.1kHz) and above, such as Tidal and Qobuz.

Second, with respect to the amps, I would ask whether you really need this much power (at least, for your first serious hi-fi system). The Bowers & Wilkins 705 S2 speakers are relatively easy to drive, so they don’t need that much power. Unless you have a very big room and listen at high volumes, I’d urge you to get the Audiolab 6000A integrated amp I reviewed in October 2019. This will also provide you the flexibility of a volume control, multiple inputs, and a built-in digital-to-analog converter. You could connect a CD player, turntable, or streamer down the road, or even use its Bluetooth capability to wirelessly connect a phone. In my opinion, the 6000A will easily drive the 705 S2s to very loud listening levels in most domestic environments. Also, consider that with your Walkman connected directly to power amps, just forgetting once that you’ve left the Walkman’s volume control up too high before hitting play could be disastrous for your speakers.

With respect to your choice of speakers, I highly recommend you listen before you buy, if possible. Sonically, a pair of B&W 705 S2s does all things very well. In particular, the bass, midrange, and imaging precision are simply amazing given the price and size. The one downfall is that the 705 S2 has a little too much treble energy and can sound a bit bright. Whether you like this will depend on your personal taste, and how loud you like to listen. If you like to listen loud, you may find some recordings sound too bright. At lower volumes, you may in fact like how the B&Ws provide more air and spaciousness compared to other competing speakers. And remember, reading my comments is no substitute for going out to a dealer and listening for yourself. Best of luck. . . . Diego Estan

Digital Output from a Chromecast Audio Streamer?

To Doug Schneider,

Thanks for reviewing the Heaven 11 Billie integrated amplifier-DAC.

I have a question regarding your setup. What is the “partnering TosLink interconnect” you refer to in this sentence, and how are you using it with the Google Chromecast Audio streamer? You wrote: “I connected a Chromecast Audio wireless streamer ($35, discontinued), using its partnering TosLink interconnect ($10, discontinued), to one of the Billie’s TosLink inputs, so I could wirelessly stream uncompressed music from Tidal.”

I have a Chromecast Audio but only ever used its 3.5mm output jack to connect to the RCA input of my AV receiver. So, I am wondering how it can be used with TosLink.

I’d like to ask one more question. When I play Tidal over Bluetooth it uses the Masters setting, but I assume the quality is ultimately lowered due to the limitations of Bluetooth transmission (even with aptX). However, when I use Tidal over Chromecast Audio it reverts to HiFi quality, as you mention in your answer to Kiran’s question. So my question is whether Bluetooth or Chromecast Audio offer better quality from Tidal. I suppose the Masters setting on Tidal via Bluetooth is misleading since it gets compressed later on?


Great questions!

What many people don’t realize is that the little Chromecast Audio jack outputs a digital or analog signal, depending on the type of cable you connect to it. Currently, you are connecting your Chromecast Audio to your receiver with an analog cable that has a 3.5mm connector on the Chromecast side and RCA connectors on the receiver side. When connected with an analog cable, the Chromecast uses its built-in digital-to-analog converter (DAC) to output an analog audio signal.

If you purchase what’s called a mini-TosLink cable—which is a digital optical cable that has a 3.5mm connector on one end and a TosLink connector on the other—and connect that to the Chromecast Audio and the other end to the TosLink input on your receiver (all receivers have them), the Chromecast device will automatically bypass its own DAC and shoot out a digital signal to your receiver via the TosLink cable. This allows your receiver’s DAC to convert the signal from digital to analog. Depending mostly on the quality of the DAC in your receiver, this may be a better way to connect your Chromecast Audio.

When Tidal outputs in HiFi mode, the resulting files are streamed at 16-bit/44.1kHz resolutions. Tidal’s Masters setting outputs the proprietary MQA format, which, using a lossy compression algorithm, can pack high-resolution music files (e.g., 24/96 and 24/192) into 24/44.1 or 24/48 files. When you stream wirelessly with Bluetooth, the bitrate, regardless of the flavor of Bluetooth codec used, is lower than 16/44.1, so any file listened to that way will be at a lower resolution. The Chromecast Audio can support resolutions up to 24/96, but, unfortunately, Tidal’s software won’t stream higher than the HiFi setting (i.e., 16/44.1) to it—that’s why, even if you select Masters, Tidal will always revert to HiFi quality when streaming begins. Still, I’ve found that many music selections still sound great at the HiFi setting, so it’s not that much of a deficiency. I hope these answers help. . . . Doug Schneider

Go with a Purifi-based or Parasound Power Amp?

To Doug Schneider,

Thanks for a helpful, illuminating write-up on the speaker everyone wants to know about—the KEF LS50 Meta.

You mentioned listening to them with your Purifi Audio demo unit, and it seems you liked the pairing.

On the topic of commercially available Purifi Audio power amps that might be just perfect for the Meta—the NAD C 298 power amplifier [using Purifi Eigentakt technology] is available everywhere and lists for $2000 (in USD).

I was wondering if you knew whether the C 298 is in the SoundStage! review pipeline at all, and more generally, if you think it would be a smart choice to audition with the LS50 Meta.

I’m stuck between going sorta brutish and old school with a Parasound Halo A 21+ amplifier or submit to my futuristic, energy-efficient overlords and go Purifi. Without boring you about all my gear, I’ll just say I think I have a neutral DAC and strive for a neutral but lifelike and engaging sound signature out of my speakers—now or in the future.

Thanks again!

Tony A.
United States

So many audiophiles fear change, so they get stuck in the same rut with old-school products when, in many cases, they could have something better. Parasound makes very good amplifiers and the A 21+ could make you happy, but I strongly encourage you to have a look at NAD’s new C 298 power amp. I’ll let the cat out of the bag and tell you that we have it in the review schedule and, in my opinion, this amp should be on the shortlist for anyone looking for top-flight amplification, even if they’re willing to spend multiples of its price. I hope that helps. . . . Doug Schneider

Only Incremental Improvements: KEF LS50 to LS50 Meta

To Doug Schneider,

It was with a great deal of curiosity and interest that I read your review of the new KEF LS50 Meta loudspeaker.

I have five of the original LS50s in my theater and, having read the sales pitch, I was most curious how the Meta would measure. Pulling up the old SoundStage! Network measurements for the LS50 to compare, it looked as though you were just measuring another LS50. The differences, for the most part, could be put down to standard production variations as much as to any new refinements.

It was interesting that they really couldn’t improve the cabinets at this price point, but not altogether surprising.

The biggest difference I can see in KEF’s literature is that their Metamaterial Absorption Technology virtually eliminates the back wave of the tweeter and reduces total harmonic distortion (THD) by around 0.03%. So that’s, maybe, a 4dB reduction. I’d consider that to be no more than an incremental improvement.

The LS50 has as close to the ideal temporal response as you can get with a passive speaker. That being said, it’s not perfect -- it can be improved by forgoing the passive crossover and biamping the speaker with a digital speaker processor. Using FIR and steep IIR filters, you can tweak these speakers to be as close to perfect as they can be. Add in some serious digital signal processing (DSP) like Dirac or DEQX and you will have perfect group-delay response.

In other words, the improvement in sound quality from the slight reduction in THD afforded by the Meta can easily be matched by using room correction and an effective DSP crossover with the original LS50s. Yes, this is a more expensive way to go, but it does offer greater control than you can get with the wireless version of the Meta. Whether the sound would be drastically better is another story.

One thing that does suck is that KEF doesn’t offer a single LS50 Wireless II to use as a center speaker, so that model is out for me.

So, as it stands, I’m only three stereo Purifi Audio Eigentakt amps (for left, center, and right) and a couple of DSP units away from having as great a surround system as you can get with my LS50s. I’m good with that! And no, I won’t be going the active route with the surround speakers, either.

So, Doug, thanks for another very informative review.

All the best,
Jeff Henning
United States

Thanks for reading and responding. It’s true the differences between the LS50 and LS50 Meta are small, so there probably are other ways to improve the sound of a system rather than swapping out the older model for the newer one. Still, I think fans of the original will be pleased by the small improvements and, in many cases, will want to make the move. . . . Doug Schneider

KEF LS50 Metas with a Sub

To Doug Schneider,

I enjoyed the KEF LS50 Meta review.

It would be interesting if someone matched them with a quality subwoofer and then compared them to more expensive speakers with better bass. Would such a setup be better for less money?


I agree that matching the new LS50 Metas with a topflight subwoofer would be a good thing to do. In fact, I hope someone who has writes in. But time permitting, it might also be something I do. . . . Doug Schneider

Taking the Fun Out?

To Doug Schneider,

You are taking all the fun out of home audio by deviating from faith-based, subjective audio reviewing.

Just tell everyone that the item being reviewed is fantastic in every way and it’s the best thing you’ve ever heard -- with the possible exception of something similar you reviewed 18 months ago that was just slightly better. Now that’s audio reviewing.

Your scientific approach is ridiculous. What does science have to do with audio?

As for the IsoAcoustics zaZen I isolation platform, I’m not surprised that its performance was marginal. I have IsoAcoustics Aperta speaker platforms under my KEF LS50s, which are stacked on Rythmik Audio subwoofers on the left and right channels in my home theater. I wasn’t worried about the speakers vibrating on the subs, but rather, the vibration of the subs modulating the sound from the speakers. While the Apertas helped, their efficacy was not what I’d hoped for. To improve their performance, I then added Sorbothane hemispheres to the top and bottom of the platforms and, voilà, they work great! If I turn the mains amp off and crank up the subs, the LS50s hardly vibrate to the touch.

I already knew that such issues are highly dependent upon the mass of the item that’s being isolated and the frequencies to be damped, but your review really drove it home. Too light or too heavy an item and it works poorly or not at all. Also, that several damping layers are better than just one. Honestly, a platform made from a piece of Corian or a 1/4″ carbon-fiber plate sitting on Sorbothane hemispheres could work way better and be much cheaper. Or even 3/4″ plywood. And also, what is the platform standing on? How sturdy is that and how much is it vibrating? A turntable on a magnetically levitated concrete slab that’s next to a subwoofer is still going to get the crap vibrated out of it through the air when you turn up the volume.

This product isn’t exactly snake oil, but one size does not fit all. That is its failing.

I haven’t played a record in over 15 years, but my turntable sat on the concrete mantle of a huge stone fireplace throughout the 1990s until 2004. That is acoustic isolation -- unless there’s an earthquake!

All the best,
Jeff Henning
United States

I can appreciate a little sarcasm from time to time! However, I’m glad you pointed out that the IsoAcoustics zaZen I platform isn’t “snake oil.” It’s not. But as you pointed out, the effectiveness of the zaZen platform will have a lot to do with what’s placed on it and what it’s sitting on. I still think it’s a good product for the price. . . . Doug Schneider

Thanks for the Purifi Eigentakt Measurements

To Doug Schneider,

I am writing to thank you for your most recent article on the measurements of the Purifi Audio Eigentakt amplifier. I found it so enlightening and revealing that I’m seriously considering the purchase of the NAD Masters M33 integrated amp, even though some of its measurements are not quite as good as the Eigentakt itself.

I am a blind person and your article was most useful because of the written descriptions of what was shown by the graphs -- very useful for those who can’t see.

May I make a suggestion? I realize that this might be a bit more work, but providing brief explanatory notes on the highlights of speaker measurements you publish would be a huge help. At the moment, only the graphs are shown, with the exception of the sensitivity ratings.

Again, a whole lot of thanks!

Yvon Provencher

Thank you for the feedback. You make a good point about the speaker-measurement graphs -- let me see what we can do going forward. . . . Doug Schneider

Perfect Amplifiers for Under $3000?

To Doug Schneider,

What a great job with your Purifi Audio Eigentakt measurements review.

Purifi Audio’s Bruno Putzeys has stated something to the effect that audio amps are becoming commodities in so much that, at this level of performance, they have no sound signature; so, the only consideration for the consumer is the output power needed. Seeing these measurements, he’s right.

Given that most listening rooms have a background noise of 25 to 30dB and that it’s really not healthy to regularly listen to music at levels higher than 105dB, we have, at best, a range of 80dB to enjoy our music. The human auditory system can discern sounds 20 to 30dB into background noise. So, this means that we have a total range of 100 to 110dB for listening.

Considering all of this, distortion and noise are inaudible with an amp like the Eigentakt or Benchmark’s AHB2.

As long as an amp is load invariant driving a passive speaker with a crossover, it is considered to be perfect. Of course, passive crossovers are the muck stirred up in the water. Their reactive nature is problematic, but a DSP can negate the specific variations caused by a passive speaker’s impedance. Going fully active with DSP correction and FIR crossovers will negate all of the passive problems. So, with these amps in an active system, the amp is no longer a factor in the sound quality at all.

You can get a Nord Acoustics stereo Purifi amp with all its options for about $2400. For a triamped system that uses powered subs, two amps to drive the mains would cost less than $5000. Used in this way, the Eigentakt would be as perfect as an amp can be. To our hearing, it would be perfect.

So that’s it. Amps, now, perform better than we can hear and the two best stereo amps on the planet cost $3000 or less.

While the world runs toward self-destruction, we are making some fantastic audio equipment.

Jeffrey Henning
United States

Let’s hope the world gets better and more people can appreciate these wonderful amplifiers. Thanks for your feedback. . . . Doug Schneider

Does Purifi Represent a Turning Point?

To Doug Schneider,

I have been involved with audio/hi-fi for many years and it really seems to me that there are more and more manufacturers and importer-distributers who are solely trying to grab the brass ring. They are not at all interested in introducing the next generation to quality audio reproduction. It appears to me that there is a never-ending number of these industry people who want to sell higher- and higher-priced gear to a shrinking customer base. There is no big picture, and, as a result, they will be responsible for their own demise.

My interest in audio/hi-fi began as a young consumer, developed later as a partner in a specialty audio shop for six years, and continued as an informed consumer for many years. In actuality, few, if any, improvements have been made since the ’70s to mid-’80s. I recently listened to a system belonging to one of our old customers, consisting of Rogers LS3/5A speakers, a Dynaco ST-70 amplifier, a passive ladder control, and an early Burr-Brown-based multibit DAC. I listen to most of what is offered today and it in no way approaches this system. It’s fantastic. I heard a pair of Dynaco A-25s about a year ago and they were really nice. No wonder they were the all-time best-selling loudspeakers. Yes, there are fine examples made today; however, on a price and general availability perspective the consumer is at a loss. We simply do not need audio jewelry that costs as much as or more than our car or our home.

I believe that we are at a turning point and technology will assist in bringing the experience of quality audio reproduction to a wider audience. I was hopeful about the Tripath-based amps a few years ago as they were inexpensive and very good. Then Texas Instruments bought out Tripath for their patents and disposed of the company and its products. So, with all of that, I believe the likes of Benchmark Media Systems and Purifi Audio are on the right track. Original thought and more affordable applications will hopefully expose quality playback to a larger audience. I would really like to see a review of the entire Benchmark stack of the basic DAC3 B, the LA4 line amp, and AHB2 stereo amp rather than a random sample of each component. This might be an interesting project for you guys to take on. Another product line to look at is the PSI Audio brand of professional powered monitors. They are very good; they have been around for more than 35 years and started as an OEM for Studer monitors before Harman bought out Studer. This is a unique line of high-quality speakers utilizing class-G amplification.

I found your article and review of the Purifi amplifier and monitors very interesting. I am curious as to which of the Hypex switching power supplies was used in the prototype amplifier. In reviewing the Hypex DIY parts site, it seems that there are three power supplies that look similar to the one used in the amplifier that you reviewed: SMPS1200A180, SMPS1200A400, and SMPS1200A700. Do you know which of these is the unit used in the amplifier you wrote about?

I do believe that this is the future of audio/hi-fi. Primarily, I have used push-pull directly heated triode amplifiers. With the eventual demise of NOS power tubes and the importance of energy efficiency going forward, it is important to find alternatives that can perform to expectations. It was only a matter of time until switching amplifiers matured to a high standard. This benefits everyone and will make the hobby more accessible to more people. This can only be a good thing as the current entrance fee is simply out of reach for many.

Thank you for the article and bringing this information forward. I find the work in this area to be eye-opening and of great interest.

Best regards,
John Shepherd
United States

What you wrote really struck a chord with me -- I mostly agree. But does Purifi amplifier technology represent a turning point for hi-fi? I believe it does, but we’ll have to see what the marketplace says. By the way, the Hypex power supply used in their evaluation amplifier is the SMPS1200A400. As a rough estimate, then, combining that power supply with two Purifi 1ET400A amp modules and the Purifi gain board -- which they sell as a package called Eval1 -- plus wiring and case should cost less than $1500 USD. That represents incredible value for such high performance. . . . Doug Schneider

Purifi, Pass Labs, or Hegel -- In Search of an Amplifier for Magico A5s

To Doug Schneider,

I read your review of the Purifi Audio 1ET400A amplifier and wanted to reach out to ask a question.

First of all, I am not an audiophile -- I have had to Google what a source, a DAC, an amplifier, and so on, are. I ended up investing in a pair of Magico A5 speakers, and my challenge now is to build a setup around the A5s while entering this (confusing) hi-fi world.

My first thought was to go with a high-end integrated amp, such as Hegel’s H590 or Pass Labs’ INT-250 -- both apparently used by Magico themselves. A more hi-fi–savvy friend of mine described these amps as “mustangs -- raw power but not very modern" and recommended looking into the latest Purifi amps and a decent source like Lumin.

As a technology person, I am attracted by the story of Purifi Audio and their goals, but I lack the reference point and experience to judge whether this is a good fit. Could a Purifi setup drive the A5s, and how would it differ from high-end integrated amps like Hegel and Pass Labs?

Best regards,

You certainly have a great set of speakers to partner with a fine amplifier! The trouble is obviously figuring out what to choose. In that regard, I agree with you that the world of hi-fi can be confusing -- mostly because there are so many choices, but also because everyone out there seems to have a different opinion. Obviously, this response reflects my own opinion on what you should do.

Because you’re new to hi-fi, I think the fewer components there are in your system, the better off you’ll be. Therefore, you’re on the right track considering an integrated amp for your speakers. An integrated amplifier has, at minimum, preamplifier and power amplifier sections all in one case. Going at it this way will give you great sound without a lot of complexity or fuss.

But before I get into what I’d recommend, please understand that the Purifi Audio amplifier that I’ve been writing about isn’t a commercial product -- it’s an engineering sample that uses their 1ET400A amplifier modules, which they supply to other companies to implement in their amplifiers. As a result, no one can buy this unit at a store. But even if you could, it’s only a power amplifier, so you’d need a source, such as a digital-to-analog converter (DAC) with a volume control, which is what your friend is recommending (a Lumin product), or you’d need to marry up the source with a preamplifier so you can adjust the volume. But I have some good news if you want to go the Purifi route . . .

The first company to license Purifi’s 1ET400A amp technology was NAD, with their Masters M33 integrated amplifier. Roger Kanno just reviewed the M33 for us and absolutely loved it, and he pointed out it has more features than most integrated amplifiers do. Not only does it have preamplifier and power amplifier sections, it also has a built-in DAC, a moving-magnet/moving-coil phono stage, Dirac Live room correction, and streaming capability based on the excellent BluOS software platform (developed by Lenbrook Industries, NAD’s parent company), among other functions. The M33 also puts out a decent amount of power -- it’s rated at up to 200Wpc into 8 ohms, which is plenty for typical setups.

The Pass Labs INT-250 and Hegel Music Systems H590 integrated amps you mentioned are also good options, with both providing more power than the M33 -- the INT-250 is said to deliver 250Wpc into 8 ohms, while the H590 is claimed to output 301Wpc into 8 ohms. Magico speakers tend to like quite a bit of power, so the INT-250 and the H590 might be better options than the M33. However, that will depend a lot on the size of your room and the volume levels you listen at.

The main downside of the INT-250 is that it is a barebones integrated amplifier -- there are no additional features beyond its preamplifier and power amplifier sections. As a result, you’ll need an external DAC if you plan to play digital music (which is likely since that’s what most people listen to these days), as well as an external phono stage if you’re planning to use it with a turntable -- something you might want to get into later. Therefore, for you, the better choice between these two is probably the more powerful H590. In addition to being an integrated amplifier, the H590 has an excellent built-in DAC and provides streaming capability via UPnP, which isn’t as full-featured as BluOS but still gets the job done. The H590 doesn’t have a phono stage, mind you, or the other features of the M33 I mentioned, so you’ll have to determine what your exact needs are to know if it’s right for you. Chances are, it has enough features.

All told, for your situation, I’d go with the NAD Masters M33 or the Hegel Music Systems H590, with the latter having more power and a decent set of features and the former having a plethora of features and less power -- though the power it delivers is based on Purifi’s cutting-edge amplifier tech, which seemed to intrigue you. I have little doubt one of those products will fit your needs perfectly. You make the final call. . . . Doug Schneider

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