Depends which Pass amp, a lot of the Passlabs poweramps are very low input impedance, which are not very freindly to most high output impedance tube preamps.
Do your home work first the output impedance of the preamp should be at least 3 x or more lower than the input impedace of the poweramp it has to drive.
Cheers George
Do your home work first the output impedance of the preamp should be at least 3 x or more lower than the input impedace of the poweramp it has to drive.
Cheers George