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
It should be better than a Rotel, I had the 250 for about 2 days and returned it.  In all fairness, I did purchase it used from The Music Room.  No problems returning.  It just is underpowered.  I had sold an old Adcom 555ii which would beat it hands down, no tubes too, and sounded sweeter.  I like PS Audio's marketing and return policy and the people - but the stuff is not high end in my opinion - right in there with MAC and Rotel.
@plaw - was that the BHK250? I don't have any comment in regards to their power, efficiency of your speakers, size of your room or the listening levels you enjoy..

I do know that a BHK250 does sound markedly better with the BHK Pre, honestly I can't speak as to why it's the case. But it is just so.
Contact PS Audio and explain your situation. They have some pretty decent tech people that can make the right suggestions. 
Even though they are "factory direct" now they have a good team of engineers.