Best way to wirelessly transmit audio within house

CD player downstairs. Denon receiver (using zone 3 to feed house speakers) UPSTAIRS. I cannot get a clean signal due to walls and floors. I have tried FM (CRANE) - not enough range, Motorola Bluetooth (nope) and closest of all, Audioengine W1. The signal gets there all right, but there's way too much noise hiss and hum under everything. The problem is interference, likely from something within the Home Theater equipment, i.e.: is not in the amp or the house wiring. Can you suggest something?
Outlaw Audio OAW3 ? I use these to transmit music from my computer to HT system, and to transmit LF from my main system to powered sub. Everything is on the same floor, nevertheless I experience great sound quality and zero interference, despite an assortment of interference-generating devices running in the home.

The OAW3 has a transmission range of 200M line-of-sight/50M through walls. The Audioengine W1 has a listed transmission range of 30M, but does not say whether that is line-of-sight or through walls. If you are attempting to transmit a signal beyond the range capabilities of the products you have tried, you will experience poor performance.
Thank you - I ordered a pair.