There was recently a discussion on one of the forums in Germany where someone complaint about the sound quality of his MP3 player which was connected to the TV port of the RNS-D. The repsonse was that the RNS-D is using a special equalization for the TV port which is optimized for the OEM TV tuner. Using the TV port for a MP3 player may require an additional equalizer (or source which allows you to change the output) to adjust the build-in sound schema.