The more I listen to these the more I like them.
A little background on me.
All my listening has been done on mid-fi headphones, and while I have auditioned maybe a dozen different pairs, unfortunately all I was focused on at the time ( a year ago or so) was hearing forward vocals, and what bass quantity the HPs could provide, any of the more subtle characteristics escaped me. I never found anything I liked better than my first pair.
Then I bought a pair of modded 225i from DavidA, and they opened my ears to an entirely new listening experience. Instrument separation, clarity, and detail as I had not heard before. Then bought a pair of B-stock Audeze EL-8O, and they took the clarity and detail to a new level. I very much like these Audeze, probably my favorite HPs.
For me, the modded 225i have a little more bass than what I would consider "ideal". The Audeze, being planar has a gorgeous bass, with appropriate quantity of bass, though at times I wish there was more bass.
Now to these Magnums.
The highs are just a bit too much for me, but the Audeze have the same affect to me. On a whim a few weeks ago I bought a Schiit Loki Mini. Using this to dial back the highs just a bit, I thought they transformed the Magnums into a headphone I could listen to for hours. Detail and clarity were not affected, at least that I could tell. I think the bass quantity on fleasbaby's build is just about perfect. Bass when I need it, without overpowering the rest of what is going on, just spot on.
To sum up: Superb detail, clarity, and instrument separation, with as close to perfect balance of bass I have heard yet. I have yet to build a HP myself, but am considering giving it a try. This driver is one I'll be considering, and these cups, as others have noted, are beautiful!
Thanks to fleasbaby for allowing me to hear these.