best pre-amp for Pass F6

@audiouli sorry to revive your thread, I am wondering what pre you choose in the end for the F6..

My case will be a bit different, provided you have enough input signal (from digital), I would be looking at a B1 (which I already own) for an F6, or maybe would a passive 10K-20K or an active muses control given the F6 input buffer suffice too?
 
Thank you guys, I shall be looking then at: DAC < DCB1 < 20K volume pot (20K Alps, Muses or might have a 50K stepped Elna around) < F6 and probably speaker protection.. let's see!
The choice of the case is not easy in this period of time, but given the difficulty to choose I will then probably house the DCB1 in a separate case..