I really like the Amphony wireless audio transmitter. I have the model 1500 transmitter/receiver. It has rich bass and nice, smooth treble response. In fact, I have an Apple TV, but I use the Amphony unit instead. I have the transmitter connected to the line out on my Mac Pro. The receiver is connected to my TV, which is connected to my stereo. I use my TV to centralize inputs, as my stereo only has one line in (it's an older B&O system from the early 1990s).
I have A/B'd the difference between AirPlay -> Apple TV vs. the Amphony setup. Both are patched in through my TV to my stereo. The difference is obvious. The AirPlay -> Apple TV setup has tinny and brash highs. I like to listen to 70s jazz fusion, like Weather Report, and when the drummer is slamming away on the cymbals, it just sounds awful. The bass is thin, which does no justice to Jaco Pastorius' bass lines. The Amphony setup is much better. The bass is rich and full, the treble is smooth, and the stereo imaging is better. I have my speakers set up such that I sit at the vertex of an equilateral triangle between the speakers, much like one would do with studio monitors, but with more distance. The stereo imaging is much better with the Amphony unit.
The cool thing is I can remote control iTunes on my Mac (in another room) with the Apple Remote app on my iPad or iPhone. The improvements with iTunes 11 make it a pleasure to use. Sure, I don't get album art on my TV. I simply turn off the display on my TV. The album art is on my iPad. The music quality is most important to me. Of course, one may question why I don't play vinyl on some fancy tube amp system. I like the convenience of having music at my fingertips. I'm too lazy to get up and fiddle with records.
I wrote up some of this on my site, in an article about Apple TV's poor audio quality
. Don't get me wrong, I love my Apple TV and use it all the time. It's just not audiophile quality. The Amphony transmitter is 24-bit. As I mention in my article, Apple TV is apparently doing a sample rate conversion on-the-fly, which damages the sound. If you have Apple Lossless or even 256Kbps AAC's from iTunes, they are 44.1k. AirPlay to Apple TV converts this to 48k. Whatever is happening, it doesn't sound right to me.
One tip -- if you have strange artifacts and popping sounds with your Amphony transmitter/receiver, it is most likely that your wi-fi router is interfering. Just pick another channel for the 5 Ghz band on your router, and it will solve the problem. I use an Apple AirPort Extreme, which is a really nice wi-fi router. I put the 5Ghz band on channel 32, and it works well now. The default (automatic) did not play well with my Amphony setup.