Well, i think there wasn't on amazon the 80ohm version, or it was way more expensive than the 250Ohm, but as i said i can still return the 990 Pros, in fact i tried now both the DX3 Pro+ and Zen Dac V2, and i think i liked more the zen dac v2 (Actually in A/B comparison i couldn't hear any difference, but the zen dac is cheapier and has the bass boost function, that i enjoyed, ngl).
So i would like to try other headphones too, even if I have to spend 400 euros (headphones + dac/amp if needed)
So did you ultimately end up going with the Zen Dac V2? I've got that, the DX3Pro+ and the SMSL C200 sitting in front of me. I have the Sennheiser 660S and honestly, there isn't "much" difference between the 3, but I can tell a difference from the Zen Dac and DX3/C200. And nit picking some of the instrument separation, I prefer the C200 over the DX3Pro+. BUT - I do love me some bass in certain circumstances (EDM, metal, etc). So I love that the Zen Dac V2 can push some extra bass. I'm really torn.
1) I had issues with the Zen Dac V2 not working when my computer would awake from sleep. Resolved that with a USB2.0 driver and plugging it into a USB2.0 port. I also had to plug-in an external power supply because driven by the USB, my PC would freeze randomly for 5-10 seconds.
2) The DX3Pro+ just........works. It always works after sleep and power on and connects. I have no problems with this unit functionally. I do prefer the sound of the C200. I never installed a driver for it.
3) The C200 I like the most for sound quality (minus the bass), but it randomly stops working! It will come back from sleep, but will just randomly stop working. I've tried running it without a driver, and with a driver.
I have until the end of January to return the units I don't choose. Presently I daily drive the Zen Dac V2 just to put it to the test for a few weeks. I plan to switch to the C200 again by itself (unplug everything else so there's not a bunch of crap plugged into all my USBs) and see if I can get it work consistently and see if I can still enjoy this without the extra thump. I think I have pretty much ruled out the DX3Pro+. It's good, but the Zen Dac V2 is good enough and the bass boost pushes it over the edge for me. Unless I could truly get the same effect from an EQ setting. Then I might consider keeping the DX3Pro+ over the Zen Dac if I can't solve the C200 problem.