I've had this setup for a few days now and I'm really enjoying it. I've decided to play around with the gain switches and found some subtle, yet audible, differences. In particular I find the result using setting 5 awesome. It really gives a soul to these headphones, while I found the base setting 3 to power them fine, but result in a less "emotional", maybe more clinical presentation. What are you experiences with it? Also, is there a "recommended" setting with 600ohm headphones - if one wants to approach this from an impedance-matching point of view? I found the MKIII reference guide rather confusing wrt this. Thanks.