Mono LP's?

no..its no big deal

Cool thanks all. Got it!!

If you use a stereo cartridge you need to jumper the left and right signals, preferebly right at the cartridge. However, if you also play stereo LPs it is more convenient to do this in the preamp with a switch. DON'T do it at the power amp output!!

What this does is eliminate the cartridge's sensitivity to vertical groove modulation, which in the case of a mono recording is pure noise. Some cartridges sold as "Mono" are actually stereo models with the jumper installed internaly.

Old records, especially 78 rpm ones, should be played with a larger "needle". Some cartridge mfrs. offer such stylus for their stereo cartridges.

No and yes.

No you don't have to play mono recordings with a mono cartridge.

Yes, playing mono recordings with a mono cartridge will sound better.

A simple fix: Withstand the use of a mono switching on your pre-amp and with a stereo cartridge on you TT just get two single ended 'y' adapters one with male stereo RCA's and one with female stereo RCA's. Connect them so that the two single RCA ends plug into one another, taking the stereo output of you TT and "blending" if you will the two signals together and then exiting as a two channel output of mono from the other end going to your pre-amp. This is essentially what Eldartford mentioned, I believe. It will effectively cancel the vertical groove modulation and render your monaural vinyls far more quietly.

Happy Listening!