GOgroove SMARTmini BT ADVANCED Wireless In-Car Bluetooth FM Transmitter with Charging, Music Control and Hands-Free Calling for ANDROID, iPhone, Blackberry and Windows Smartphones
I only connected this unit through the auxiliary port and it sounded very good through my car speakers.  The problem I find with the GOgroove is the in-unit microphone is too far away from the person using it.  There needs to be a external microphone so it can be placed near the user.