Expandable 6 source Multi-Tuner. This unit comes with dual AM/FM Tuners built in, then you can customize it by adding additional tuner cards depending on the type of tuner you want to listen to. Add HD Radio, or Satellite Radio card and you are ready to go! Music anywhere in the home just got easier with Denon’s TU-604CI multi-zone tuner, which is equipped with dual independent AM/FM tuners, each cable of storing up to 56 of your favorite stations. The modular expansion capability provides 4 open tuner expansion slots, allowing optional slide-in tuner modules to be easily installed. 3 optional tuner modules are available – choose the ACD-AMFM card for expanded AM/FM tuning capability. Select the ACD-XMSIR card to add XM or Sirius satellite radio home tuners* – install two ACD-XMSIR cards to enjoy both XM and Sirius services. Add the ACD-HD card to receive the growing number of local stations broadcasting HD Radio. Mix and match any of the available tuner cards to suit your listening preferences. Custom Integrators will appreciate the web-based programming functionality, third party remote control system compatibility and Remote Access via the Ethernet connection, which also provides firmware update capability. An RS-232C serial port allows another port of control with popular home automation systems, and the infrared input/output ports provide additional control flexibility. *XM Connect and Play tuner, Sirius Home Connect tuner sold separately.