I wonder what kind of setup would make a Jot sound compressed, just as a useful bit of info. In fact I find it kinda' surprising cause my experience was pretty much the opposite. For the HD650s I think the Jot is among the few solid state amps that actually feel like they have plenty of heft to give the bass proper punch. Couldn't be bothered with all the technicalities and maintenance of tubes, but the fact of the matter is that most commercially available tubes have no issue making these cans easily powerful, while solid-state stuff was a very hit or miss (in my limited/amateurish experience). As soon as you plug them to a Jot, the mid range and the bass immediately step up a few notches. Small modi dac, Schiity cables, and it just works, dude. I'm actually a bit wary of switching to any other combo in this range or trade it because of the mid-range heft it has. Maybe they tried it cold and it biased their conclusions? I think it's a bit weaker until it warms up.