I have to mention a ZMF headphone that doesn't get talked about a lot any more, but that might do the trick for you: the Eikon, the closed-back headphone that uses the same bio-cellulose driver as the open-back Auteur.
If you like the TH-X00, you're probably OK with a closed back (Eikon). You're probably OK with an upper midrange that can seem a bit emphatic on certain tracks of certain genres (Eikon). As for the rest:
- I thought the Eikon's bass was a master class in dynamic driver bass: it went very deep with authority (real sub-bass); sounded pretty flat through the entire bass range; and conveyed plenty of nuance and texture of each bass instrument
- The rest of the frequencies were on par with bass quality: midrange is large, expressive, detailed, but not rubbing your nose in it. Upper mids could be a bit truthful at times, but choice of amp & DAC affected that greatly; and the treble was all there, but didn't shovel "air" into your ears, making the entire hp sound tipped up
- But maybe the best things about the Eikon were above and beyond frequency response. The Eikon has spectacular dynamics, really upper tier. It also has far above average soundstaging for a closed back. I'm not sure I've heard better soundstage from a closed back, and this was way before ZMF's highly effective ADS feature
The musicality of the Eikon didn't hit my ears like that of a 650, but that was mainly because it was closed, had such great bass, dynamics, and soundstage. In any case, the musicality is definitely there (there's just something about a biodynamic driver).
- I owned both a TH-XOO (mahogany) and E-Mu Teak.
- To my ears the Teak was the better headphone, but neither one really is in the same league as the Eikon sonically (my 2 cents).
PS: The only reason I sold that gorgeous padauk Eikon was that closed back dynamics tend to aggravate headache and tinnitus for (especially when they sound great and I want to crank it!).