What are the advantages to a Class A amp & what are the trade offs?

My 70 watt Class A EAR 890 has 8 itty bitty storage capacitors while my 130 watt Class A/B monoblocks have huge 3" X 7" pair of storage capacitors each. The McIntosh MC30 sounds like it is 3X or 4X more powerful than it’s rated. My voltage regulated Class A/B amps can drive low impedance speakers with ease, stay cool and sound great. Maybe they are inferior in some sonic ways, but they are superior in most others. I will stick with my amps and you can have your F5 which I am not sure is a single ended or push-pull design. The great sounding, huge and hot Class A tube amps I’ve heard are usually single ended.

@viridian The Krell you refer to (KSA 250) is an older model. The KSA 300S was the next series that were designed precisely to run completely Class A unless the amp gets very hot. Here's the article that explains the difference:

https://www.stereophile.com/audaciousaudio/krell_ksa-300s_power_amplifier/index.html

BTW, with my low sensitivity speakers (Mirage M3si) I can drive the amp into the highest bias level - and it gets really, really hot. What I don't know is whether or not the top two bias lights still turn on when the thermal protection kicks in. It may be that for some of my extremely loud listening the amp goes into Class A/B. For the great majority of my listening the amp never goes past the third bias level and according to the article, and everything else I've read, the amp operates in pure Class A. I think it's worth noting that this amp weighs 185 lbs. It was obviously built to an extremely robust standard.

To clarify further, operating in Class A was the whole point of this amp's design and explains the design differences between it and the KSA 250.

“The Krell KSA amps are pure Class A.”

The only Krells that were full Class-A biased into 8ohms were the KSA50 and the KSA100 and KSA100 MkII monoblock, all these were internal chimney heat sinking and fan forced.
https://youtu.be/kqSkh08AmKM?t=1

Cheers George