I use my phone in my car all the time, just jack it in to the AUX jack and adjust as needed. Not a stereo expert, but I would think that since the TP isn't designed with an amp & large speakers in mind in needs something (i.e. a head unit) to make the components interact as desired. Could be wrong, but I have seen plenty of posts where the TP sound is piped through car audio (via some kind of connection to a head unit) just fine
