This is easy! I just auditioned the Audeze with the E.A.R. HP4 Valve Headphone Amplifier by Tim de Paravicini. Superb. The HP4 powered the phones sublimely and cleanly like no other headphone amp could do. The audeze will never be neutral, ultra detailed cans for the recording enthusiast...

I have auditioned all 3 of your top list and bought the HP4. It is by far the most flexible with high Z and low Z inputs and single ended and balanced outs and much much more. Its a fantastic heirloom piece and you will never part with it. Tube rolling is a joy and yields remarkable and precise...