is there a big difference in quality and spl between the 2 connections to an amp.my kx600.1 has both.my rca output on my hu apparently crapped out on me when i did my big 3.so i tied in to the rear speaker outputs and ran those wires to the amp and used the plug for speaker level inputs to the amp.it sounds o.k. but not near as good as before with the good rca input.(but much better than with the bad rca input)im gonna get a new deck because of this,i just wanted to make sure that there is a big difference in sq and spl using the rca's instead of speaker wire input.if not then maybe i got a diff, problem