While technically true, you can trick it to allow you into using your head unit remote. That's how I ran mine, never had any problems with it.The bigest difference is a software update that allows you to use your headunit volume controll with the 660, where the 650 REQUIRES you to use the volume controll on the remote for the processor.
Almost got everything right, but the H650 does have a remote.H650 has no remote, H660 does.
"The workaround for this is to use the "aux input" on the h650. Set the volume on your headunit to max before clipping. Now turn the volume up on the h650 to as loud as you can, preferably using a disc that was recorded at low levels. Leave it at that volume and turn down the volume on your hu. Now, you can use the volume control on your headunit... with the caveat that AntEQ will be disabled. For my TSX, that wasn't a problem for me at all since the frequency response of the headunit is ruler flat past half way (20/40 on the knob), and I think the mild bass/treble boost at that low of a volume didn't affect sound quality in the least."how did you trick it?