John; you posted the MONO DVD question in another forum. Perhaps some of your answers will be found in that forum since I made a posting there. The TV LOGIC mode you describe may in fact be the expression equal to MONO MOVIE that I have used. It is possible that TV LOGIC may only work with analogue connections and not digital ones. If you have an unused input on the receiver, hook up a pair of audio output cable from the two channels of your DVD player to an unused analogue input on the Onkyo 600. Your manual may indicate which analogue inputs will work with TV LOGIC.

Now as to that amp in your car running the subwoofers, BRIDGING has been going on for many years in uptody,uptody home power amps and if I recall some quad int. amps of the 70s just to name a few. Accordingly, you had a few ways to use this power amp in your car so you bridged from stereo to mono to power the two subs. But lets suppose you did not bridge and each stereo amp was run seperately to each subwoofer. Sub output sound is mono, so you would have had to split one output feed into two output feeds from you car receiver's sub out( if that is what they have for a car like they have on your home theater receiver); one feed into the left amplifier input and the other feed into the right amp input. Would this give you better bass? That I cannot say. My home theater uses a separate stereo amp that is fed by a single audio output interconnect that has what is known as a Y connection. Note the letter Y has two splits at the top. One goes into the left input and the other to the right input of the power amp section of my stereo amp(a NAD 3240PE). The NAD cannot be bridged. I use two passive subs in two speaker cabinets with this amp.