Hi all,
The SA-5000 has two sets of input jacks for phono: one MM and one MC. The MM inputs are suitable for cartridges with outputs of about 1mV and up, and which like a 47k load. The MC input is for cartridges with outputs lower than 1mV, and offer front-panel switchable loads of 47k, 1k, 300 and 100 ohms, with a "user" position that loads the cartridge with whatever resistor you install in the preamp. The preamp was not intended to support two tonearms at the same time: you have to decide ahead of time, plugging your tonearm into the appropriate input and setting two internal switches to the "MC" or "MM" position, depending on which input you're feeding signal into. The internal switches select betwen the two inputs and configure the first stage of the phono stage into either a common-cathode triode voltage gain stage of about 24dB (MM), or a JFET/triode cascode with a gain of about 46dB (MC).
Hope this helps.
Michael Elliott
Alta Vista Audio LLC
www.altavistaaudio.com