Cons of using main XLR/Balanced outs for subwoofer?

@atmasphere

Ralph said "So if you have a balanced output on the preamp and a single-ended input for the sub, the ISO-MAX Jensen box is the elegant solution". 

Question/clarification...since the ISO-Max transformer has a single ended input and a single ended output, are you using something like this Neutrik adapter to go from preamp balanced out to transformer rca input?

Neutrik NA2FPMM 3 Pin XLR Female to RCA Plug Adapter (parts-express.com)

Question/clarification...since the ISO-Max transformer has a single ended input and a single ended output, are you using something like this Neutrik adapter to go from preamp balanced out to transformer rca input?

No.

The Jensen ISO-MAX can be supplied how you need it- for example with a balanced input (that is how mine are set up) and a single-ended output. That is specified when you order it.

Plan to use my Rowland Concerto integrated amp to drive my Salk Song3 mains full range and preamp output to a chain of 4 active subs in a Distributed Bass Array. Would like to do the Audiokinesis Swarm eventually but right now have to use existing subs from home theater system. The Rowland is fully balanced from inputs to outputs, with  2 sets of balanced XLR outputs, no unbalanced outputs. First option: balanced output A to a Jensen Transformer Iso-Max PC-2XR (2 Ch XLR in/RCA out), then RCA into L/R inputs of sub #1, then daisy chain to rest of subs somehow using either dual or mono RCA connections. Option 2: Rowland balanced out to balanced inputs of a Revel Performa3 B110 sub, then begin daisy chain using mono RCA output.  Already have the Revel sub and Jensen Transformer model, rather not have to buy the Jensen SUB-1RR unless that is truly better. The Revel sub also has mono XLR out but looks like XLR inputs are only found on hi-end/cost subs or pro gear, so likely just sticking to low cost good DBA subs with RCA inputs like the SVS-1000 Pro (already have a pair). Option 1 could use the summing circuit within any sub like the SB-1000 Pro to start the chain. Option 2 uses the Revel (maybe better circuitry?) and means I don't have to use the Jensen with its extra cost and cabling. Would really appreciate input on these options or others from Ralph @atmasphere and anyone else on XLR/RCA issues with multiple subs. Thanks

I'd use the Jensen transformers if I were you.
The problem you can run into is that of ground loops when interfacing single-ended and balanced equipment. The transformers sort that out by providing ground isolation. They won't rob you of any impact as they go down to nearly 1 Hz.

2 followup questions to your helpful response. The straight Rowland to Revel connection would be balanced. Are you thinking the balanced to single-ended interface inside the Revel might not provide ground isolation like the transformer so hum could show up downstream in the daisy chain? Second, any significance to fact my Jensen PC-2XR is rated flat to 10Hz vs the flat to 1Hz of the SUB-1RR?
Thanks