RCA phono cables to XLR Preamp.

My moving coil preAmp - AR only accepts XLR cables, and my tourntable cords has two RCA ends plus ground. I was told I need
a -4 +12 step up and balanced adapter? Can you help? Where can I buy a good one?

Thanks, David
I would suggest you skip the adapters and simply have your tonearm leads properly re-terminated with XLR's. Sound quality will probably be better and cost may actually be less, certainly not a lot more. I believe this kind of termination may be problematic with Rega arms, but if you are not using a Rega, it's unlikely you'll run into too much trouble. Take it to a qualified tech and have it done.
Try out the B.A.T. adaptors (about $80 a pair).