It would be interesting to have someone compare some recent Class A componenets with those of 5 or even 10 years ago. it would be interesting to know how much the industry has evolved, what they old componenets might be reviewed at now and where the biggest/smallest advances have been.
Because I am so nuts about music, I listen to just about everything that comes down the pike. Living in a large metro area (Los Angeles) allows for this. I think the general answer is "yes" -- even the top stuff in Class A gets incrementally better. I doubt if it improves at the same rate as mid-priced gear, because of the trickle-down effect and economies of scale. I suspect that is why you specified Class A and not B or C. I have heard the old JM Labs Grande Utopias, for instance, and the newer "BE" model is a shade better, to my ears -- a bit more dynamic and open. The new Triangles are just a bit better -- a wee dab more refined and weighty. You will notice that the Class A list of speakers has a few entries from 3, 4, even 5 years ago still listed. Class A electronics are more difficult to evaluate, for me, since system synergy means so much when you match electronics to speakers. I'll leave it to JA, Wes, and some of the other folks who contribute to the list every 6 months to answer that one. This is an interesting, provocative topic. Clifton
In the case of preamps, I can tell you there has been tremendous change over the past 10-15 years. Class A sure ain't what it used to be!
The Audio Research LS2B was rated Class A in the early 1990s, and it was the core of my system until early last year. I bought the LS16 mark 2 then, mainly for features, and not expecting a big sonic improvement. I was pleasantly surprised by a HUGE improvement in resolution and sonic purity. There is no way the LS2B could rate higher than class C today, I would estimate.
Furthermore, as good as my LS16 mark 2 sounds, it has been superseded now by the LS17, which AR says is better-sounding, AND the LS26 and REF 3 are both supposed to be even better than the LS17. That makes me wonder if the LS16 mark 2 would even be class A now; probably not. The REF 3 is three times as much money, and The Absolute Sound says it is indeed a reference component (Stereophile has a review in the works, according to an e-mail I got from JA a month ago).
I think a lot of the sonic improvement is due to advances in coupling capacitor technology. My early LS2B had MIT Multicaps for output coupling, and in the late 1990s these were superseded by AR in later LS2B production using TRT Infinicaps, which I know were a large sonic improvement from making the same change in the input coupling of my power amp.
More recently, the Infinicaps were replaced by TRT Dynamicaps, which made a HUGE improvement in the sound of my power amp, and AR now has started using their own "proprietary" output coupling caps (Dynamicaps in a plain brown wrapper...??) in the REF 3 and the LS26.
There have certainly been power supply improvements and also the change from the 6DJ8 to the 6H30 in the AR preamps, but I suspect that something like 50-60% of the sonic improvement in the latest AR preamps is due to the improved coupling capacitors; AR certainly spends a lot of money on these caps, and they make a huge sonic difference.
As an experiment, I upgraded my old LS2B by removing the old MIT Multicaps and replacing them with the Dynamicaps after I bought the LS16 mark 2. It did not bring the LS2B quite to the level of the 16, but I would say that 50% of the difference between them was eliminated by this change; a major improvement without question.
For anyone with an older preamp, I would strongly recommend installing the Dynamicaps in the output coupling; for $100 or so, one can acheive a sonic improvement that is very audible.
Fact: The Audio Research LS2B was Class A rated in the early to mid 1980'S (used it 10 years). Not Bad.
Fact: The LS16 Mark 2 sounds much better than the LS2B (used it one year+). Very good.
Fact: The Reference 3 and LS26 sound MUCH MUCH better than the LS16 Mark 2 (I recently purchased the LS26). Sheer Magic!!
Lots of evolution there!