There are further considerations beyond RIAA equalization and gain.
Moving magnet phonograph cartridges are designed to work into a specific load, typically 47k ohms and 250 pF (e.g., see "Recommended Load" for a Shure V15 on http://www.shure.com/v15vxmr.html), which is significantly different than the load presented by a microphone preamp. The wrong load will change the frequency and transient response of the cartridge.
Phono preamps are designed to present the correct load to a phono cartridge. Good ones have switchable loads to accommodate different cartridges and to compensate for the capacitance in the connecting cable. In high-end gear, it is common practice is to modify the input circuitry of the preamp to specifically match the cartridge and cable in use.
There are also moving coil phono cartridges, which have different requirements.
By contrast, professional microphones typically have source impedance of about 150 to 200 ohms and are designed to be loaded with a pure resistance in the range of 1 to 5 k ohms. (here are the specs for a Neumann U87 http://www.neumann.com/infopool/mics/en/u87ai_t_data.htm).
If you are serious, my recommendation would be to use a dedicated phono preamp. There are some very good ones for around $150 like the Parasound PPH-100, which handles both MM and MC cartridges.
Menlo Park, CA USA
Jan Depner wrote:
> I just had a similar problem. I was getting hum from my receiver/amp so