prinzmetalzThat's a good question. For what it's worth, when I've seen it discussed, it seems somewhat split, but most of the comparisons seem to favor the m1060. I ordered one and am getting it in tomorrow. I demoed the HD650 but don't have one, and I don't know that I want to keep buying more headphones. At $200 and a decent shipdate I might have still got it, not so sure at $250 and the long ship date.
M1060 is $300 and they ship pretty fast.
NateBI own the 400i's. I think they are amazing. Beats my TH-X00 I think but not by much. I'm curious to compare when I have these but I also heard the 650 in store and they are great too. So Basically you don't go wrong with either. The negative for me for the 400i is that the cups being large, when I lean back against the couch they are being pushed forward, like they reach the back before my head does, maybe my head is small but it's a minor confort issue.
prinzmetalzI have both and love them both. If you use a tube amp, stay away from the M1060. Through a solid state amp the M1060 is punchier and has stronger bass, but the sound of the HD 6xx is very enticing and resolving too. I tend to use the 6xx mostly with my DarkVoice... they sound amazing together!
prinzmetalzThere was a lot of talk on head-fi about a weekness in the design of the 1060 that made the wooden ring crack. Maybe they fixed the issue but a few month back it seemed like it was happening to a lot of people. My 2 cents, don't want to bash on Monoprice I haven't heard them
prinzmetalzI know at some point after the first run they where not available for a while. Monoprice is a company I like, maybe after the first run they took a step back and perfected their design, It's possible because it took some time. I was interested at the time but ended up buying 400is
NateBI use Grace m9xx (clean, full signal on 90) through to DarkVoice with RCA 6AS7 and 1950s Sylvania Bad Boy. To my ears this combination is resolving and opens up the soundstage.