If you choose to go with a line in wire you have an option of using the usb connector, or the audio out jack with the TP2 I believe. If you use a usb audio or video cable adapter, then you can get then so you can apply power to the cable and get an audio feed and a charging conection at the same time..
They can be found easily on ebay
If you have RCA inputs one audio/video cable:
http://cgi.ebay.ca/TV-AV-Out-Cable-U...item518e634f0e
If not there are adapters that give you a 3.5 out and a mini usb in:
http://cgi.ebay.ca/Original-HTC-USB-...item2a034e8acf
I use a audio/video cable and feed into a video deck so I van view youtube etc as well.