Hi DGX-670 users. Just bought mine. I am having a difficult time, trying to record on more than the first channel. It let's me record the CH1, but when I go to record another channel, I press record and the channel No. It brings up the box/channel your recording...I finish that channel record, and when I want to listen...I only hear channel 1 and I don't even see the light on the new recorded channel playback, where it suppose to be recorded...