2A3 vs. 845

Here's a message I posted on AA. I'm going to post it here as well for a larger audience.

What a stupid title for a thread, eh? :-}

I'd read a number of times comments such as "the larger triodes just don't have the magic of the smaller 45s, 2A3s, etc". I never quite understood how/why that should be and largely wrote it off as probably either largely untrue or insignificant.

But I made a discovery recently. I have a pair of 845 SET monoblocks and a small 2A3 integrated that retails for about 1/5th the price, both from the same maker, and the 2A3 sounds better on sensitive speakers. It just sounds more open and effortless - it does microdynamics better - those subtle fluctations in voice and horns that make music sound so alive.

Why would or should this be? I *think* the smaller amp has only one gain stage vs two (it shares a single dual-triode driver for both channels) and that could certainly make a difference. And of course, yes, I am not comparing apples-apples here in a lot of ways.

So, in general, what is there about big vs. lil tubes that could or should make the latter preferable? Simplicity of the circuit? What else? How about the power supply. When you've got a giant triode, even a just-adequate power supply is very big and heavy. With a 3W amp, it's *much* more feasible to do a seriously overbuilt power supply. Indeed, going by how long each amp continues to play with the power shut off, and their consumptions, the 2A3 amp wins that one by a wide margin.

What else is there? If anything? Comments are very welcome!