Well, actually, the main reason for my experiment is that after 10 years of listening my system has started to sound a bit thin and harsh on the treble.
I don't know what to blame here, I've replaced drivers in my HD600, valves in X-CAN V3, but it's still the same... not like before - silky smooth and enjoyable.
Maybe it's my older ears or brain, I dunno... Will see if some Schiit helps. Maybe some other components in my X-CAN got old.
The source was changed, though. I was using an old MF X-24K DAC for many years (and it was great).. but I don't think my new MF V-DAC II is worse that that.
It has to be much better.
I think you should try the HD650 when you get a chance, as you know they're smoother than the HD600.