Check and make sure the amp you are using input impedance is a good match for the PS Audio preamp. If that is not a good match you will find the bass is rolled off big time.
PS Audio BHK lacking..
I bought a used PS Audio BHK preamp to replace my Rotel. It sounds thin with no depth & bass compared to my Rotel so I let it run for over an hour with no change. I'm new to tubes so I'm looking for ideas. New tubes or what?