Babs, the audio signal from the cdg player is much stronger than the signal from the 203g playing from the cav files on your external hard drive. Some cdgs are recorded with a stronger single than other cdgs, but not as different as playing files verses playing cdgs.
Leave all the settings on your amp/mixer the same "except" lower the gain on the player/203g channel a few notches when switching to the cdg player. Before your show, you can play a song on the cdg player, listen from your monitor, then play the matching song from you hard drive and note what gain levels were comparable to your ear. Either mark the points, or remember what the point difference was, and use this as a starting point. Of course you have to remember to lower it when you play a cdg, and raise it back when you go back to the 203g.
The only other thing I can think of, is to run the 203g and the cdg player to seperate channels on your mixer/amp, and using your av switch, only for the video.
Now the 203g "does" have a volume adjustment, and you should have it at maximum(though it might produce a hum at maximum, but hopefully not). Pretty sure you can 'only" access the volume function with the 'remote control"(hope you didn't throw it away
), and I don't know if it will stay at that volume after being powered off.
Now the tripple tray player may have a volume function only on the remote also, but I don't think so....but check for one.......