PS Audio BHK lacking..

Something definitely sounds off with that particular unit's performance, and I suppose it could just be worn out tubes or poor tube choice.  I ran one for ~3 years with much satisfaction.  It replaced a VAC Ren Sig II convincingly in my system, and I only moved on for an AR Ref 40, which does offer more, but doesn't exactly embarrass the BHK pre.  I found soundstage depth and bass to be strengths of the preamp, not weaknesses.

Trying a new set of tubes is a good place to start.  Check out the PS Audio website forum for some detailed discussion threads about the many varieties that are possible, with a nice number of sonic impressions reported.  After comparing 10 different varieties, I was smitten with Amperex 7308's in the unit, because it offered the right balance of fullness in mid-bass through low mids that my system needs, while not sacrificing the highs.

Since you have a used unit, I'm assuming it is well broken in.  Several have reported some big changes in their first 100 hours (wasn't a big event for me when I broke in a new one).

Interesting on your experience on the Psvane tubes.  Just goes to show how system synergy and personal preferences are so important.  Most folks on the PS Audio forum have preferred alternatives, as have I, but that certainly doesn't invalidate yours or anyone else's experience.

@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.

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.....