I tried a used 2x12 XXX combo and a 'new' display model 2x12 JSX combo in a store today. Same guitar, same cable, same wooden stool. I suspect both amps were defective/damaged, though.
Surprisingly, the XXX seemed the more versatile of the two. Both the Crunch and Ultra channels had a broader range of tones on tap as their gain knobs were raised from 1 to 10. In contrast, the JSX's Ultra channel had little or no difference in gain anywhere in the 3-10 range. It seemed to go straight to saturated and stay there. (Turning the gain knob back and forth and hearing no change reminded me of a Chevy Citation I used to drive that had a steering wheel totally unresponsive 20 degrees in either direction from center. I would freak out my friends by yanking the wheel towards oncoming traffic but maintaing a straight and steady course.)
Also, neither Fat switch on the JSX had any noticeable effect on its tone whatsoever. Is their contribution supposed to be more discernable in certain situations vs others, say, only at really low or really high gain settings? I had the channel volumes at 12 o'clock and the master volume at 10:30 or so if it matters.
The XXX wasn't totally without quirks, either. The Clean channel was plenty loud with its volume at 9 o'clock and the master volume at 9 o'clock, but the Crunch and Ultra channel volumes needed to be well past 3 o'clock to be audible at all at the same MV setting. I've played through this exact same XXX, and others, before without experiencing that problem, so I figure it was due to something having recently broken or burnt out or whatever.
And speaking of breaking, I've seen roughly a dozen used XXX or XXL combos for sale in local stores in the past two months, and all but one of them was missing a control. Not just the knob, mind you, but the pot's shaft itself appeared to have been shorn clean off at the face of the amp. I had a XXL volume knob shaft crack off in my hand this afternoon. A little chunk of it fell to the floor, and I can't say for certain, but it seemed more like plastic than metal. Anyone else experienced or heard this about Peaveys?
Surprisingly, the XXX seemed the more versatile of the two. Both the Crunch and Ultra channels had a broader range of tones on tap as their gain knobs were raised from 1 to 10. In contrast, the JSX's Ultra channel had little or no difference in gain anywhere in the 3-10 range. It seemed to go straight to saturated and stay there. (Turning the gain knob back and forth and hearing no change reminded me of a Chevy Citation I used to drive that had a steering wheel totally unresponsive 20 degrees in either direction from center. I would freak out my friends by yanking the wheel towards oncoming traffic but maintaing a straight and steady course.)
Also, neither Fat switch on the JSX had any noticeable effect on its tone whatsoever. Is their contribution supposed to be more discernable in certain situations vs others, say, only at really low or really high gain settings? I had the channel volumes at 12 o'clock and the master volume at 10:30 or so if it matters.
The XXX wasn't totally without quirks, either. The Clean channel was plenty loud with its volume at 9 o'clock and the master volume at 9 o'clock, but the Crunch and Ultra channel volumes needed to be well past 3 o'clock to be audible at all at the same MV setting. I've played through this exact same XXX, and others, before without experiencing that problem, so I figure it was due to something having recently broken or burnt out or whatever.
And speaking of breaking, I've seen roughly a dozen used XXX or XXL combos for sale in local stores in the past two months, and all but one of them was missing a control. Not just the knob, mind you, but the pot's shaft itself appeared to have been shorn clean off at the face of the amp. I had a XXL volume knob shaft crack off in my hand this afternoon. A little chunk of it fell to the floor, and I can't say for certain, but it seemed more like plastic than metal. Anyone else experienced or heard this about Peaveys?
I already dig (properly functioning) XXXs, 5150s, and 6505s, so I had really been looking forward to spending some quality alone time with a JSX. 
