Mono LP's?

Mono cartridges are available. You don't have to have a mono cartridge to play a mono LP.

You can play mono lps with a stereo cartridge. The reverse, however, may not be true--some mono cartridges would be, at best, hard on a stereo LP.

Mono cartridges are of interest because they can offer better performance for a mono LP since they are designed for the specific task. IA mono cartridge should pick up less surface noise, and offer overall better performance. However, the downside is that it costs more--between $50 and $100 on up for the cartridge, and you need to have it set so it's either on a removable headshell or on it's own turntable. Thus, if your mono lp collection consists of two or three records, it's probably not worth it. But if you have a large collection, it could be a good investment.

There is a good review on Audio Asylum about one mono cartridge. (http://www.audioasylum.com/cgi/m.mpl?forum=vinyl&n=265943&review=1)

No.

Only to play them at their best. For me, the Sumiko celebration works fine on mono lps and can only imagine how much better it could get. My phono stage has a mono or stereo switch so that takes care of any problems down line. Some preamps also have a mono switch, a neat little item that should be more common