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.

I have a pair of 600s and a Rel G2, I think, the one with the smaller driver. It’s been several years since I bought it. I tried the special wiring thing with the lfe cables and resistors. I had 1000ms before the 600s. It was a real pain in the ass and never worked right. I’ve used a line out of a preamp to feed the sub and haven’t had any problems since.
Thanks  dalims4 for your reponse.  Someone on another thread led me to the use of a Jesen IsoMax isolation transformer between my 600i's and my pair of subs (I purchased JL Audio E-110s).  The E110 is optimized to perform best with the low level RCA inputs.  So I am now hooked up as follows: Furutech Speaker Reference III cables with bananas both ends from each 600i amp to Harbeth SHL5+ speakers. 12ga. Cardas speaker cable with bare ends from each 600i amp into the high level input terminals on a Jesen SC-2NR Isomax isolation transformer.  RCAs out from the IsoMax to each sub.  Sounds great and is ABSOLUTELY DEAD Quiet!  But I would like to try the JL Audio CR-1 crossover unit someday.  Unfortunately, it's retail price is the same as my pair of E-110 subs.  However, it would probably allow me to maximize the synergy between my subs and my Harbeths.  Until then I can listen with what I now have and enjoy its full range sound.
Oops.  Should have reviewed my response BEFORE posting.  My amps are the Bel Canto 600M not 600i.  The 600i is my Questyle CMA 600i DAC/Headphone amp.