What could I expect to hear from a Class A amp?

I should have made it clearer. The 4-5 hours is going from standby to full power on. The standby mode is just not enough. So to rephrase the question, did you find the standby mode insufficient to let 30-60 minutes at full power to finish the job?

On separate issue, would all that heat for 24/7 at full power take toll on the circuit board? Of course the counter arguments would be the on/off as you said, and the expansion/contraction fatigue cycle due to the hot/cold. Do you know what's the typical age of a class A amplifier before the heat kills it. At least the XA60.5s are hot but not that hot.

I'm confused about the comment on Henry Ho. The DAC is either positioned between the transport and the preamp, or is part of the preamp itself. Yet we are talking about the amplifier here. It comes across that you actual benefit from improvement to your source instead.

My class A runs damn hot.
It really needs a week of warm up before sounding it's best?
On the advice I got calling the Sugden factory, I turn mine off between listening sessions.

"On separate issue, would all that heat for 24/7 at full power take toll on the circuit board? Of course the counter arguments would be the on/off as you said, and the expansion/contraction fatigue cycle due to the hot/cold."

Spatine - the only perishable component inside of SS amp is electrolytic capacitor (other than ON/OFF switch). Rush current does nothing to electrolytic capacitor other than heating it slightly (very short time and very low ESR) in spite of large momentary current. Electrolytic caps die of dehydration. Each increase in temperature of 10 deg Celsius cuts their life in half (water evaporates from electrolyte). Eventually drier capacitor has higher ESR and starts heating up to the point of runaway. In critical application (lots of current) they get to thermal runaway and explode (they have fuse to relieve pressure). The other way to damage them is to leave them without voltage for years. Aluminum oxide layer that serves as isolator is eaten by electrolyte but presence of voltage builds this layer back.

Fairy tales about rush current (turning ON) damaging equipment comes from two sources. First is the bulb or tube that breaks on power ON since cold filament has many times lower resistance. Second is the fact that if you do anything around your amp like for instance moving speakers while amp is OFF and create short it might damage amp when you turn it ON and you will blame turning ON (rush current).
Sometimes also mechanical component tends to break at start-up like for instance computer's hard disk.

Circuit boards, resistors, film and ceramic caps, transformers etc last forever even in extended temperatures. As for semiconductors - as long as they operate at sensible junction temperature (let say under 125 deg C) they also last forever. There are electronic circuits with semiconductors being turn ON/OFF hundreds times a second and they last for over 25 years. Simple example of it is seven segment multiplexed display.

As for sound being optimal after a week of continuous operation - it's possible. I don't have class A amp, don't have experience with them and perhaps less than "golden ears".

People who calculate reliability are probably ready to kill me for saying all this but statistical analysis they use is something else. When I walk with my dog we have statistically 3 legs each. Also statistically tattoos are causing motorcycle accidents.

It takes about 1 second of on time for a solid state amp to sound its best. The last piece of electronic equipment I saw that took any longer on time to sound its best was a tube television set from the 60's. (cannot speak for tube amps of today). Even that TV took only a few minutes to settle. Turning the amp on and off between listening sessions will not change the amp's lifespan in any meaningful way. Nor does an amplifier that is on but not driving a load use a great deal of energy so it shouldn't change your utility bill anymore than leaving a porch lite on 24-7. In short, these issues are of no more practical significance than the issue of how many angels can dance on the head of a pin.

>>03-16-09: Musicnoise
It takes about 1 second of on time for a solid state amp to sound its best<<

If you read Nelson Pass' comments on his First Watt products, he feels it takes about an hour for them to reach optimum performance.

Not one second.