This part is just for the record...
CTS 500 Provides 2 Video _input_ from codec or from optional DMP.
Technically you can use a regular HDMI video feed other than a DMP (no audio
over HDMI), but only DMP is supported and you may experience difficulties with
other sources like a laptop or DVR which Cisco TAC and TSBU might not assist
you with.
To answer your question for OUTPUT, you also have an extra HDMI in CTS to connect the HD video cable to the HD video display connection (Auxiliary display, projectors, ).
http://www.cisco.com/en/US/docs/telepresence/cts_500/500_assembly_guide/500_first_time_setup.html#wp1083393
http://www.cisco.com/en/US/docs/telepresence/cts_hardware_options_upgrades/cts_Hdware_O_and_U_500.html
The CTS-500 has different audio connectors: It is designed for two
speakers, a left speaker and a right speaker, you want to install external speakers or amplify existing audio?