So my sub is now connected (soundsplinter rl-i *300rms) Its running at 2ohm so it should be matched perfectly with channels 5+6 bridged getting the rated 300w. However it feels like its WAY underpowerd... perhaps MAYBE getting 100rms. Its in a sealed .6cuft box as suggested by soundstream.

Now Im still not getting any sort of bass out of my midbass 6.5 Infinitys. Their just not outputting anything decent. They should be recieving 50rms each out of channels 3 and 4.

I dont have anything on channels 1+2 currently.

Now I only have a single preamp out on my current deck - so I have it running into 3-4 inputs on the amp. (I have inputs 1-2 open) There is no dedicated input for the sub.
Does this matter a whole lot? Do I NEED a pair of Y-adapters to split up my single output out of the deck? Or would it be better to wait for my new deck and just run another set of RCAs out of it back to the amp?

Thanks for any help.