Why not just use a decent quality adapter, female RCA to male XLR ?
Saves you the cost (and sonic degradation?) of another IC from junction box to phono preamp.
Here's a pair by Cardas, shipped for under $120:
https://www.ebay.com/itm/Cardas-Audio-Female-RCA-to-Male-XLR-Adapter-Plugs-FRCA-MXLR-Connectors-Pair...
Saves you the cost (and sonic degradation?) of another IC from junction box to phono preamp.
Here's a pair by Cardas, shipped for under $120:
https://www.ebay.com/itm/Cardas-Audio-Female-RCA-to-Male-XLR-Adapter-Plugs-FRCA-MXLR-Connectors-Pair...