I think in my case, it is a combination of the factors Pedalbuilder mentions (the Concert has cleaner cleans than the Peavey), and Sumi hit it with his SuperReverb vs. his little 5 watter. The Peavey by comparison warms up and saturates a bit sooner than the Concert, and I think that makes a difference too.

@Markb, When I turn on the vibrato on the Concert, a feature at least the vintage Vibrolux shared, it is more forgiving sounding. That is probably the onboard effect covering up some stuff.

Interestingly, I often prefer the Concert without a drive pedal on, and with just the amph and the guitar, with a little verb, or the vibrato turned on. That is very nice clean sound that can have some nice warmth, and is much more complex and less direct and in your face than the 1x12 Peavey.

Interesting. Like I said, I love them both for different purposes.