How do you wire a mono cartridge to a stereo pream

With a y-adapter, which would have a jack to mate with an rca plug, and wires the signal from that jack in parallel into two rca plugs. Cheap ones are available at Radio Shack; better ones elsewhere.

But you should check what loading (resistive and capacitive) the cartridge is specified for. The resistive loading it will see is the preamp's input impedance divided by two. The capacitive loading would be that of the cabling, plus the preamp's input capacitance multiplied by 2. The capacitance may be hard to determine, but I suspect you'll be fine as far as both parameters are concerned.

The other question, though, would be if the cartridge is intended to work into the standard riaa phono equalization curve that modern preamps use.

Regards,
-- Al

I should have phrased the last sentence of my previous post: is the combination of the cartridge and the recordings you will be listening to a suitable match for the riaa phono equalization curve that modern phono preamps use? If not, overall frequency response will not be accurate.

Regards,
-- Al

Who's mono cartridge?
How many connector points does it have?
I have a Lyra and it is a mono cartridge but has 4 connections so there is no y connector needed. The manufacturer did all the work internaly.