I just ordered HD650's (and a balanced cable) to go with the Jotunheim. I've enjoyed the Grado PS1000e with the Jot, but there are times the brightness of that headphone just becomes fatiguing. I thought about sending the PS1000e to Moon Audio and having them balanced, but I'm not sure that would make a difference? Probably make it even worse (the brightness). I didn't notice the brightness so much with the WA7 amp (which I still have). So I might have to set it back up as well.
But, in the meantime, I wanted to find a headphone that would pair better with the Jot (Especially since I love what the Jot has done with my speaker systems). So I went ahead and ordered the HD650, so I'll get a chance to see what everyone is talking about. I've read lots of good stuff about the HD650 that's for sure. Both on this thread and its main thread. One poster said by running it balanced with the Jot, it sounds really amazing, and that's what I'm looking for, with not as much treble fatigue (as I'm getting from the PS1000e and I've read people get with the HD800s). I have a set of AH-D2000's too, and in some ways I was preferring them over the PS1000e with the Jot. They are darker of course, and have quite a lot of bass. They don't have the sound stage and detail of the PS1000e, but they were easier on the ears without that brightness. I'm hoping the HD650 can be a sort of "endgame" for me, at least for the next couple of years. I really want to hear/and thought about trying to buy the Focal Utopia with a balanced cable and hearing it through the Jot, but I'm not ready to climb that 4000 foot mountain as of yet if you know what I mean.
The 650 sounds like a good solid headphone. It once was Sennheiser's flagship I read someplace. Gosh, people with otherwise expensive stuff, like 7000 dollar amps, I've read in their profiles they're using the 650 as their main headphone, or one of them.
So here goes, got my fingers crossed! I hope, as others have posted that they are a match made in heaven with the Jot (and the mimby feeding the Jot as the DAC)