The Dayton SubLink can work with one transmitter and two receivers, provided two kits are purchased. We measured this unit -3 dB @ 6.5 Hz, it links up quickly, stays connected, has a decent S/N ratio, and in my testing proved quite immune to 2.4 GHz interference. I threw the 2.4 GHz book at it and it passed all tests, only to finally act up a bit with my iPhone literally 2" inches from the transmitter.
The latency of this unit is about 25 ms, which equates to ~27 feet of subwoofer distance, so I definitely recommend going wireless to both units unless the AVR has the ability to independently set distance for each subwoofer. Phasing wired and wireless subs using the variable phase control is also an option, but in my testing proved less optimal than starting with both subs wireless and then using the variable phase to fine-tune.
Director - Technology and Customer Relations
"What We Do In Life, Echoes In Eternity"