It's a high powered amp. Once imported by B&W, I'd give them a call for further advice as to current servicing details if needed.
I said elsewhere here this morning, use the preamp as an ornament (it's veiled in sonics from memory, as was the CA7, but may make a fair phono stage if used from the tape outputs), replace with a passive one to taste (I make NVA's here, so I'm biased, but sale or return on a P50 should quickly prove my point) and ffs, leave the bloody mains conditioner out of it, as many 'domestic grade' ones not costing thousands will slug the current available for such a big amp demand. Big amps like this need only be connected to a suitable wall socket and the large transformer should absorb most nasties coming in. Some clip-on cable ferrites could be used if you want to play perhaps..
Sorry, I'm not telling you what you want to hear, but not many here have owned or used these amps (I sold them as well as we were one of the few UK dealers for big Nak amps, which were very good but totally lacked cachet of the then inferior Linn and Naim offerings, even into 3-4 ohm loads!!!) and I think my recommendations could be borne out by your own listening.
Tear down these walls; Cut the ties that held me
Crying out at the top of my voice; Tell me now if you can hear me