Recently having issues with my upgraded Rega P1 turntable. Glass platter and Ortofon OM20 cartridge. For some reason, vinyl now sounds like garbage thru my speakers (Monitor Audio RS6's). Connects into a McIntosh C28 pre-amp, to a MC2105 amp. For a period of time, everything sounded great. Now I am having problems with the stereo mode on the pre-amp; only if I use the L to L & R mode do I hear sound out of both speakers; mono works ok. I've plugged in a digital source into the aux input on the pre-amp and everything works and sounds fine. I've tried both phono1 and phon2 inputs with the TT and same results. I think I've narrowed it down to a problem with the Rega. Bad needle? But that would not explain the stereo mode problem. At one point, the Rega sounded great. Any suggestions/ideas to point me in the right direction? It's driving me nuts.