Bel Canto REF600m with subwoofers

Hi all,
I am inquiring if any owners of Bel Canto REF600m monos are using them with the high level speaker inputs on one or a pair of subwoofers.  Especially with REL subs as I am considering purchasing a pair to use with mine.  But I have seen so many references to care needed in making proper connections at the amps speaker terminals that I am a bit gun shy.   So I would be very much interested hearing about successful use of this combination and how the wire connections at the amps were safely made.  Thanks.