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?
128x128fertguy
I really like them. Everything is smoothing out with more depth.  Worth the money.
These Kantas can be a little bright on some tunes but the tubes helped. I'm thinking tube amps next.  On we go..
Also check the tube voltage thing switch inside (see owners manual). Make sure they match the voltage of the tube that's is installed.