JAD800.4 and bridging

As a last ditch effort to try to get some volume out of my ID CTX65CS components, I decided to bridge my JAD800.4 to run just the front stage. I connected the speakers as shown in the owner's manual, set the channel to 2ch, and was advised to split the RCAs and feed both front channels on the amp with one channel from the radio, and the same for the rear. Well, turns out one of my RCA splitters must have had a short in it, because when I powered up the amp, it freaked the f**k out for a couple seconds before I could shut it off. Massive popping and sounded like a crappy 80s synth at earsplitting volume. Blew both of the (new) front tweeters. FML. checked my wiring, removed the splitters and fed just one input on each side of the amp, and figured out one of the splitters is faulty. However, with the amp switched to 2ch, it won't fade properly. Using just one RCA, I moved it to each input and got output from both front speakers. Yes, I have it bridged correctly, this isn't my first rodeo. When I switch to 4ch, I get proper channel separation. The owner's manual doesn't say anything about the 2ch/3ch/4ch switch on the input side, but it seems to be pretty counter-intuitive. Anyone have any insight on what the hell is going on? Also, I saw that it's rated at 400rms bridged at 4 ohms... I know there's no kill like overkill, but this sounds absolutely silly to me for running a pair of 6.5 components up front.