I have/had the same problem with Allnic 8000DHT pre and Pass XA60.8 amps. I was able to change out a set of the DHT tubes for lower gain tubes.
Interestingly I recently added a pair of Akiko Corelli's for noise and can increase the volume a few more degrees before it sounds loud (and I hear a lot more micro details).
The Allnic has a constant impedance volume control so it is supposed to be good without having to get past 12 o'clock- although I would like to use more of the attenuator range.
I believe my problem is the input sensitivity of the Pass is too low at 1 volt to full output. I am looking to replace the Pass with an amps that don't reach full output until closer closer to 2 volts.
The Allnic is way to good to replace.