Bought to replace the original Sony Cassette/radio in my Audi A4, The unit itself is typical Sony in that it is beautifully designed and finished to a very high standard. The supplied electrical connections were identical to those on the original unit, BUT then the problems started. At first, the unit would not switch on. Closer inspection revealed that the four wires from the car did not match those from the unit. After much head scratching and careful inspection of the installation instruction sheet (a huge sheet of paper by any standards), I eventually found a small item which indicated that for cars without an ACC position on the ignition switch, two of the wires had to be commoned. I did this but still no joy. The unit would still not switch on. Further checking revealed that on the car connector, sockets 1,2,3,& 4 were used, while on the MP3 player sockets 1,2,3,& 5 were used. The cable colours did not match so I had to revert to trial & error (plus a multimeter) to sort out the connections. Finally the unit powered on, and believe me the effort was well worth while. Superb sound (compared to the original unit) and absolutely rock steady CD playback on all varieties of CD (WMA, MP3, CD). Excellent Radio reception, although the unit seems very reluctant to display just the frequency rather than the RDS station name. For the price, this is an absolutely stunning audio unit, and the Aux input on the front is ideal when I just want to connect my MP3 player rather than carry CDs with me.