@davidmolliere have you tried the Blacks with a tube amp?
I'm curious about the "tube sound" but I've heard they have a lot of trouble with low impedance IEMs, so I'm wondering if the FIBAE tech compensates enough for them to sound good with an amp typically used for over-heads.
I usually use my IEMs but when I do pick up my cans I really want some more power behind them, but I want whatever amp I get to match well with the F4 as well, since they'll be my primaries soon. Well, soon as in two-ish months, my impression molds just arrived from southern California today, it's a long wait but I'm so excited that my build is finally starting!