"Getting back to the OP’s original post. Class A circuits ( and we are specifically talking about amplifier output stages here ), just sound smoother, more homogenized, less artificial, more involving, with every attribute of recorded music reproduction, keeping one in his / her listening seat, longer. Granted, there are still audible differences, between designers and manufacturers products, but, Class A is still, imo, superior, at this particular time, in SQ."
Well put, @mrdecibel - certainly in agreement here. I’m using the MOSFET-based Belles SA-30, which outputs 30 watts pure Class-A. 30 watts mayn’t sound like much, but the number itself is not really indicative of its ability to successfully drive a variety of low to moderately sensitive speakers, some of them quite power hungry. My own speakers are very sensitive at 105dB’s, and being a fairly easy load on top of that suddenly converts the SA-30 into a small monster; approaching -20dB (I usually never go below -25dB, and typical listening is done in the -45dB to -50dB’s range) on the attenuator of my DAC/preamp things really start to become rather scary..
I bought the Belles new about 5 years ago, and I sometimes wonder how long I can expect it to perform "according to specs" - that is, before the caps begin to wear out to detrimental effect. The lifespan of amps vary somewhat for a variety of reasons, but of course pure Class-A amps are the ones most challenged in this regard due to the heat being produced (all things being equal; pure Class-A amps are typically very well build and being topologically more simple can use fewer and better components, in which case a quality pure Class-A amp may equal or even exceed the lifespan of a lot of the better Class-A/B offerings, or so I’m thinking). From what I’ve been able to assess Mr. Belles amps are quite durable, even the ones running in Class-A, but what’s the opinion of you guys on the capacitor-lifespan of a quality pure Class-A amp - 10, 15 years, or more?