The absolute sound concept has value, but it has limitations. As real world so beautifully pointed out, the absolute sound is not a singular experience in the real world. It is a range of experiences all of which are possible within the same venue. Some like their coffee unsweetened, some like one spoon of sugar, some like two.
The most important component in any system is the ear-brain, the second is the speaker-room, and everything else follows.
I suspect that @hilde45 could add much to this discussion if he has time.
Very pertinent comments from you and @sutts as well. I am in no way suggesting that excellent (which to me means natural bass) performance is not possible with non SET amplification. I was really connecting to what @realworldaudio was explaining as it fit my listenings experiences so closely.
I wanted to make the point that a high quality SET amplifier with appropriate speakers can produce very convincing and natural bass in one's audio system. Bill I do not doubt for a momment you are not enjoying superb bas with your Atma-Sphere M-60s. It's simply the better match for your speakers/room and desires.
In that context same for me with the Frankenstein MK II with my Total Eclipse II. The correct buttons are being pushed.☺. It's all good.
Charles