I totally lost track of this thread before I replied to this....it's grown quite a bit, no wonder I couldn't find the reply again!
Mine is the desktop version, though keep in mind it's the old original generation desktop circa 2005-2006, not the newer editions. I definitely dislike the HD650's with it. All the things I thought I disliked about the HD650 were actually things I disliked about the Micro + HD650, not the 650's themselves. I seriously can tell little difference between the Micro and either my Onkyo 5xx and Denon 23xx AVRs. I really don't think the Micro's a bad amp, but I think it just doesn't play to the HD650's strengths, presumably due to a limited voltage swing. I agree that it doesn't have a massive soundstage (I've commented here that "right between your ears" is an apt slogan....because that's right where the sound is.) but it's been said that Lyr doesn't have a massive soundstage either. I found that the Micro delivered far less bass than the Lyr, though it bloated the midbass much more. All the characteristics of insufficient voltage.
I've still been too lazy to try the K702 on the Micro. Someday, I'll get around to it... Also, did your Micro have the stock power brick (mine does) or the "second chassis" power supply? That probably makes a difference.
I definitely wouldn't classify the Micro to Lyr transition as "tiny" in terms of changes. I know you're a fan of cables, and I'll say the difference is dramatically less subtle than cabling
You got it right with the larger soundstage, and the less forward mids, and a brighter treble, but that's only part of it. There was much more clarity and tonal balance to the whole thing. The Micro was extremely congested by comparison and that congestion gave way to clarity and overall balance with the Lyr. At least the old model Micro, to me, is just a terrible match to the HD650 to the point that I don't understand why they still show the 650 in the images of the micro. It's a well made amp, and I'll bet it performs well....with low impedance cans. If you like yours though, that's what counts! I also find it interesting that you like the Micro much more than the Asgard. I would have thought they'd actually be very similar in terms of voltage/current ratio for the HD650s.
It will be interesting to see you opinions if you do get a Lyr. I followed your Q701 discussion and are a good part of the reason I got the K702! (If there's merit to the warmth of the Q, I wanted to go the cold, bright, analytical route to have something polar opposite the HD650 for my collection