I use HDMI and composite at the same time. The composite are sent to a RF modulator which feeds a smaller tv in the bedroom (smaller set where HD isn't important). The HDMI to the living room tv.Currently I use all three video outputs on my TiVo HD(s) at the same time.
The composite video output goes to a couple of SD TVs with composite inputs
The component video output goes to a couple of distant HD TVs with component inputs
The HDMI output goes to the HD TV located with the TiVo.
The Stereo audio is split and sent along with the composite and component outputs. The local HD TV gets it's audio from the HDMI connection.
All three of these outputs are on all the time. Can I do this with a Premiere?