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- Created: 18 February 2017 18 February 2017
To Doug Schneider,
Thanks for your KEF Reference 1 review. Your review provided enough insight for me to make an informed decision towards buying my KEF Reference 1s -- thank you. My budget is slightly slim now and I can spring for a high-quality amp of 125Wpc into 8 ohms or a more powerful amp of 250Wpc into 8 ohms, but [the latter] is considered high value rather than highest quality. Which amp do you think would provide better service to the speakers?
Great choice on your loudspeakers! Now, let’s see what we can do about the amp.
First off, it is important to understand that in order for a loudspeaker to increase its output level by just 3dB, you need to give it double the amplifier power. As a result, all other things being equal (including both amplifiers’ abilities to drive difficult loads, which I’ll touch on below), that 250Wpc amplifier will only give you 3dB more output from your speakers than the 125Wpc one can. That’s not a lot, since a 10dB increase is required for a perceived doubling of loudness. As a result, a 3dB increase will only come across as a little bit louder. Does that little bit matter to you? You will have to decide.
Another thing to consider is how well each amp will drive more difficult loads. An 8-ohm speaker load is considered typical, which is why power ratings are always stated that way. However, that 8-ohm loudspeaker rating is more or less an average, because a speaker’s impedance varies based on frequency. For example, the Reference 1 is rated as 8 ohms, but dips as low as 3.2 ohms near the bass region, so it can be a bit challenging for some amps. To understand better how well those amps will drive your speakers, you really need to know how well they perform into 4- or even 2-ohm loads. I suggest looking into that a little more since the 8-ohm rating only tells you so much.
Obviously, based on the above, I can’t tell you which you should buy -- there’s not enough information. However, I will tell you a story about an amp purchase I made almost 30 years ago, which wound up being a mistake and might help you today.
Back around 1990, a company called Forte offered the Model 3 and 1A stereo amplifiers. From what I could tell, they were basically the same amplifiers, just that the Model 3 was a class-AB design, so it ran cooler and was rated to output 200Wpc into 8 ohms, while the 1A was biased as pure class-A, so it ran much hotter and could only deliver 50Wpc into 8 ohms (I suggest looking up differences between AB and A if you do not already know, since it’s too lengthy to get into here). Since both amps had essentially the same parts inside, they had the same abilities to drive difficult loads. They were also priced the same.
At normally listening levels, the 1A sounded markedly better than the 3A did -- it was smoother sounding overall, and there was more body and realism to the sound. Sonically, it wasn’t even close, at least at normal listening levels. But because the 3 could deliver more power, it could play speakers a little bit louder (its 200Wpc rating gave it 6dB more headroom than the 1A).
Being a young, naïve audiophile, I wound up buying the Model 3 simply because it was more powerful. I was scared that I would run out of juice with the 1A. That was my mistake. All the time I had the 3, I never used all the power it could provide and I always knew that the 1A sounded so much better and would’ve likely provided me with more than enough power. As a result, I always regretted the decision I made. That’s not to say that the lower-powered amplifier will always sound better. It’s just that whichever one you choose, make sure it delivers sufficient power and gives you all the sound quality you truly desire. . . . Doug Schneider