with the RH5 you have multiple options for sub out-
1 use high level speaker connections
2 use Y adaptors on the RCA outs
3 use the balanced out for amplifier connection, RCA for sub or vice versa.
4 use a female XLR to female RCA adaptor on the balanced out connections.
if you like a transparent, neutral, refined dynamic sound this is the one. should have kept mine.