I have a QED uPlay Puck plugged into my Hi-Fi (I'm too new to post URLs here, sorry).
It's mains powered and Rx only, so would be no good for a car, but might fit the OP's needs. It supports multiple devices - I've paired it with my desktop and laptop (both using plain old SBC compression) and my Note II (apt-X), and I can switch between the three seamlessly (disconnect Bluetooth on one device and connect it on another).
Sound quality is great, especially from the Note II (I use with with Spotify's "Extreme Quality" streaming setting).
If you wanted to connect an iPod, you can get apt-X adapters for those too. Sennheiser make a fairly decent one called the BTD 300i.
Hope that helps