Linn or rega

I'd stay with the Linn. Get the Cirkus update and look into another cart. Suspended 'tables usually will deliver a rather deep bass and soundstage. I'm confused that you should be craving more bass as the LP12 is usually thought of as having a bit of a romantisized mid-bass. Non suspended 'tables - in general - may not go as low but usually enjoy a tighter attack on the bass notes. The sense is one of punchier bass though not a deep. I like the blue point special but really favor the Benz line. Another cart that has grabbed my attention lately has been the Clearaudio Aurum Beta S. Any of those carts will work great with the Ittok.
Just give your local Linn set-up guy some time to do the upgrades and really dial in the suspension system and I'm certain you'll rediscover your 'table all over again.

That's my two cents.

P9/RB900 will bring a deal of clarity but if you want something of Linn in your upgrade, you should consider Basis1600/Basis RB300 combo that brings clarity and musicality as well.

Hi-
I'd replace the Valhallah with a LIngo (or Naim Armageddon) Power Supply, which will _really_ improve the bass. The Circus helps a bit to control the bottom end, but doesn't really extend it. Many Circus upgrade owners were actually a little disappointed with it, but I think it's a worthwhile addition - after a Lingo. I would also recommend a thorough set-up by a Linn expert. It makes a tremendous difference in performance if the suspension is "in tune."
As for a cartridge, I'd heartily recommend a Dynavector. They work GREAT with a Linn, and you just need to pick a model that matches your Preamp's input. That will certainly add the clarity you're looking for - a definite step up from the BPS. E-mail me if you would like a specific recommendation, and Good Luck!
Ed

btw

the rega 9 is coming out now with a new model 9. the arm is the rb 1000. it may be worth checking out, there are a lot of upgrades, wiring, power supply, arm, etc.