I've used Xvive U3 to transmit to Bose S1Pro (battery powered). No noticeable latency. I didn't go too far from the source, but I think it worked very well at about 40 feet. I'm using the same unit this weekend in a much larger room, and I need to run sound to a patio with no AC outlets. Fingers crossed for another successful outcome.
I also have Xvive U2 (1/4") transmitter/receiver that I use to feed signals when the connection is 1/4", and not XLR.