Alright I need some help with my stereo. I made a REALLY STUPID mistake by not letting JonyB set up my stereo as I thought I could do this myself to save a trip and some time. Someone kick me in the balls if I ever try that again.

So I've got the EXACT same setup as I had in Mariah in my Saltare. 4-XS650's in boat, an XS-12 sub, all powered by a Syn-6 amp, with a WS-420 EQ.

Now it did real good in my Mariah with a small sub box, no port.

Now in the Saltare I've got room to build the Wetsounds spec box, and I did. Now the sub sounds weak as hell, and distorts when cranked.

Start of ideas:

1) The Deck: Deck has 6 RCA outs. Front, rear, and sub. I'm running the one set of RCA's into the WS420 from the REAR rca outs. I'm thinking about running the sub RCA's straight from the deck and bypassing the WS420.

2) The amp's tuning. Which I'm guessing is my problem. JonyB and worked on it for a while to get it actually put out some sound finally. At first it barely made any noise. After turning down the gain on the components it helped, but the sound was awful. Doesn't hit well, and distorts very easily.

3) The box. I've built it to Wetsounds specs for a sealed box. My guess is ported would be better, but since Wetsounds put a 5-year old in charge of the schematic for boxes, you have to have a professional builder make one. I don't know how to make baffles and vents for boxes. I just play with my wood.

Please help. Here are the pics of the amp's controls.
The gains on channel 1-4 are down, and the Sub bass boost is actually at 1 o'clock now. And the Freq HZ for the sub is at 3 o'clock. The lower Freq HZ dial on the bottom for Channel 5-6(sub) is where it's at now.