Are you using the GMOS-04 or GMOS-01? But yes I have both of the gains on the interface all the way up. I still can't get good sound out of it.

 

I'm thinking about just running wires from my deck to directly to the factory speakers

 

Since you have an aftermarket head unit, I'd say just by-pass the stock amp. In all honestly, it's so weak that your head unit probably makes close to the same power, possibly more but I don't know the factory amp's specs. Just unplug the harness to the factory amp and connect the input and output wires for each speaker.

 

i have a gmos 04

 

How much power are your pre-outs giving?

The deck I have has 5v pre-outs and I'm getting better sound than I did with my old one which only had 4v preouts.

My deck also has a lot of other specific settings which helped me get more/better sound.. but more volts = more sound. You can start by looking at the deck you are using.

 

I just installed a Scosche GMLAN2SR interface and everything seems to be working just fine. The chime sounds the same as the factory one.
I paid $15 for it on ebay, and yesterday I saw it at walmart for $50 so I did alright on the price.

 

I used the Scosche GMSR09....it worked in that it allowed me to play my aftermarket stereo but shortly after installing the system I began having loads of mysterious/phantom electrical problems which have since gone by-bye after putting my stock deck back in.

That being said, I don't know if the problems were due to the harness or the stock deck being out of the loop. Needless to say, I have since bought a stock deck relocation harness and will buy a new aftermarket deck harness just in case that is what the real problem was.....that way when I put my new system in I'll hopefully be problem free this time around.