XLR to RCA conversion for sub

My Threshold FET 10E has two sets of outputs to amps, 1 RCA, 1 balanced. I was running bi-amped through both to two Threshold amps to B&W Matrix 802 Series 3 speakers. But one of the amps has a problem, and blew the crossover in my left channel mid/tweeter, and is blowing the rail fuse in the left channel. So while my amp is being sent to Jon Soderberg and my 802 Series 3 to an authorized dealer for repair, I still have a working Threshold amp, and an older set of 802F B&W's. Great speakers, but lacking in bass and not bi-amped. So, throw in a ASW-1000 sub which has it's own amp. My question is: as I have been up-grading to Transparent Plus or Super cables through out my system, but leaving the balanced until last. I need to go from the FET 10E to the sub via the balanced out on the pre-amp, and yet an RCA in on the B&W ASW - 1000 sub. So can I just use an XLR to RCA cable? Or should I use a balanced converter box to un-balanced? It is just a sub, so is the balanced signal good enough for a powered sub which is mono to start with? I can see where it is more critical in imaging in the higher frequencies..... Tom
Tom, I agree with your assessments toward the end of your question--I wouldn't bother with anything more complex than a cable that's built with an RCA on one end and and XLR on the other. I suggest Markertek.com--they are a broadcast supply house and sell a cable that is configured as I've mentioned. This also avoids using a converter plug and eliminates two more connections!

They are made with Canare or Belden cable and use Canare/Neutrik connectors, so the quality is actually quite decent. I was using a short pair between my Marantz SACD to BAT VK-31 pre-amp for a while (while I was building my own cable) and was never unhappy. I think they may even sell these singly. And they're dirt cheap!
Hmm, I read this and was curious. Please confirm, but in a case like this you don't get the benefit of a balanced IC since there is no balanced circuit on the receiving end, yes? It's essentially an RCA IC with an odd connector on one end.
Tonyptony, you are correct. In this case, the input to the sub isn't balanced anyway, so there's really no way to maintain a balance circuit straight through. There are numerous XLR to RCA converter plugs, ranging from high quality products by Cardas and BAT, but none of them do anything different than a cable that is terminated with an RCA on one end and an XLR on the other.

In this case, the "hot" line (usually pin #2) from the balanced output is run to the center pin of the RCA plug. Both the return and ground legs from the XLR output are connected to the neutral (barrel) side of the RCA plug. An alternative is to leave the ground "floating" at the RCA end, so it acts as a drain for any emi/rf it picks up, but in order to do this, you generally have to make your own cable.

Sorry for the lengthy response, but hopefully, it makes sense.
not a responce more of a tangent[first time ever steped into this forum been reading for three hours or so]i bought a pr of audioquest diamond x-3 xlr lnterconects and need to use [or not depending on answers]from out on scd-1 sony to input on my cat pre which is rca only. by using off market adapter can i use this cable in such a manner. the adapters are for sale on audiogon now for $30 ea. pr. and as i say are no name units. i dont mind if i dont get 100% of the capabikities of the cable because even diminished its gotta sound beter than the ruby i am now using. i am more conserned with damage to equipment. hellpp