I would like to use the balanced outputs on my 990, but there is only one XLR sub output. What are folks using for a splitter when running more than one sub on the XLR outputs?

I would assume an XLR 'Y' adapter.

I haven't heard of anybody running two subs with XLR's, and as you appear to have discovered the options for splitting that signal are tricky to find. There are a number of XLR splitter boxes around for microphone applications, but the only source I could find for a y-adapter cable was Cobalt Cable , which costs about $28.

If you are going from the 990 to something like the BFD or DEQ2496 to EQ your subs, you can use this...

http://www.sweetwater.com/store/detail/YXM121/

The price is right and the company was VERY friendly with follow up calls and great service for an under $15 order.

I use one of these for my center channel (as I use 2 centers)
- works like a champ! There is also a pro version but cost 2X and I didn't see the need.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=245-872