I have the MKIII sitting in front of me now, listening with pleasure! Before I even connected it, I switched to low-gain. (since all I use now are low-ohm headphones)
At first I didnt notice much difference when connected directly to my soundcard (amp was only warmed up for a minute or so), but kept listening and started to notice some wierdness in midrange. It seemed... I dunno... more liquid and less... rough? I dunno, but its great.
Now amp is warmed up for 30 minutes and sounding good.
This isnt very warm amp, but definetly not harsh! Quite neutral with with some tube tonality. Im 100% sure that this is because of the stock chinese tubes. Adding proper tubes would perhaps bring tube warmth to highs too. So far I think it sound really good with Alessandros aswell.
These work with Ultrasone Proline 750 really well too! The lower midrange, which is slightly empty with PL750, is bit more full.
Differences are still quite small, but noticeable. Im already wondering what kind of tubes I should roll in to enhance them...
*edit* There is one big difference though. Soundstage is quite a bit bigger. Even in some metal songs with very little soundstage limited to left and right, it sounds less annoyingly left-righty with MKIII. Screw crossfeed! With this soundstage is a lot more fleshened than what my Elite Pro can produce alone.