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