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?
No, I’ve solved the problem. It was old tubes. I’m new to tubes so I spoke too soon. surfmuz, don’t hesitate because of my screw up. Mine is sounding much better w/new tubes.
@surfmuz   It's a worthy preamp.  I ditched a VAC Ren Sig II for it, as it quite convincingly sounded truer to the music in my system.  For the money, especially used, it's a good value in sound and function.
Another big question...- is hybrid preamps like BHK much better in bass aspect then full tube units like Modwright or VAC ? Did anybody compared same price range preamps with hybrid and full tube circuitry?
Well, the BHK's bass certainly bested my VAC Ren Sig II, which retailed at a distinctly higher price range in its day.  Haven't heard a Modwright preamp.  I'm guessing the BHK's MOSFET output gives it bass authority, but you can play with tonal character with tube choices, so.....
There may be something wrong with your preamp outside of tubes-There is no way it should sound as poorly as described if all is well. What kind of amp are you pairing with? Have you played around with the current jumpers? If it is a tube issue, there are plenty of options out there ranging from the inexpensive to more pricier options. I have played around with a number tubes, including 6sn7 tubes w converter. I am currently using Siemens CCA that sound incredible, granted they cost quite a bit. My runners up are Telefunken 6922 and the Tungsrams as suggested by BHK. just be sure to get tubes that are tightly matched otherwise you will suffer from volume pops. Best of luck and hop it works out!