Obsession with Amplifiers

Letters to the Editor are not a feature of this website because in nearly all cases they are trivial and replying to them is a waste of time. The following exchange of messages is an exception.

Hi. I’ve been enjoying reading your publication online. I came across it some time ago and was highly interested, but the (as I believe was the case) steep subscription price was a barrier I could not overcome. With the new blog format and downloadable PDFs I’m glad that I can now enjoy the no-nonsense information that hopefully will help me save tons of money on audio purchases in the future.

I have a comment/suggestion for a blog regarding amplifier topologies. I don’t doubt Mr. Aczel’s points of view on the idea that all modern, well-designed amplifiers sound the same. I have myself attempted comparisons and found so little difference between reasonably matched power capabilities that it becomes largely irrelevant in the face of source material and loudspeaker design.

My curiosity about the old and tired debate over “all amps sounding the same” was piqued reading the April 2006 review of the Parasound Halo A 21 amplifier, a device that I myself have had the pleasure of owning. While impressive in capability, it certainly does seem like excessive overkill considering the equally meaty power claims of much less expensive “pro” amplifiers from the likes of Crown and QSC. The marketing difference that led me to purchase an A 21 (and subsequently some of those aforementioned “pro amps”) was in the topology: the A 21 boasts a class A output for the first few watts of output, which is the raison d’être for the amplifier’s stylistic heat sink and side fin design. The copious amounts of heat put out by the amp while in use only confirm this.

But let me get to the point. With so many new amplifiers coming out these days based on switching power supplies and ever more exotic topologies such as H, D, T, and all the letters of the alphabet yet to be used, can the idea of all amplifiers sounding the same still be applied without question? Can I put a class A Krell amp against a class T model such as the (in)famous Sonic Impact mini amp, and expect indistinguishable output given identical input and level matching?

I would love to see a commentary on this question, since it seems to be the new thing in amplifier technology, what with everyone going gaga over ICE modules and digital amps and hybrid AB/H designs for power efficiency reasons, with debate over power input having moved from $5,000 pure-gold power cords to $5,000 stabilized DC battery banks and other such exotic power generation ideas for the new digitals. Needless to say, the little ‘amp on a chip’ devices yet again seem to herald an unmatched level of sonic bliss beyond anything else on the market; perhaps understandable given manufacturers’ need to continue to sell new product. But is there really any difference this time around?

                                                                                                                                        [From] Shadow

First of all, let me disabuse you of the notion that The Audio Critic is there to “help [you] save tons of money on audio purchases.” We’d have to review hundreds of products at each price point to do that successfully. No, The Audio Critic is there to point out what’s important and what’s unimportant in audio. Big difference.

As for amplifier topologies, the sensible answer is, “Who cares?” Any amplifier, regardless of topology, can be treated as a “black box” for the purpose of listening comparisons. If amplifiers A and B both have flat frequency response, low noise floor, reasonably low distortion, high input impedance, low output impedance, and are not clipped, they will be indistinguishable in sound at matched levels no matter what’s inside them. Of course, some of the new “alphabet soup” topologies do not necessarily satisfy those conditions.

I really believe that all this soul-searching, wondering, questioning, agonizing about amplifiers is basically unproductive and would be much more rewarding if applied to loudspeakers instead. For various reasons that I have discussed in the past, people are more willing to change amplifiers than loudspeakers. That’s most unfortunate because a new and better loudspeaker will change your audio life but a new amplifier will not.

                                                                                                                                                 —Peter Aczel