I installed the cdx, soldered wires, everything works, but the sound quality is terrible. bad cdx or am i bad at soldering?

where did you get the CDX ? ,and did you check all the wires ! Sounds like you may have a wire crossed
The looms that you can get have been known to be wired in th wrong pins. I know I had it happen. Just because its a red or pink wire make sure its the right pin to pin don't always trust the colors!

What's bad about the sound? Background noise, all chanels? Bad ground makes lots of noises, that's where I would start - and then recheck your wires from the pin out on the DIY thread.

the ground is the same ground for the gmsr1 sirius... sirius doesnt have any noises, I guess ill tear it apart again and match pins... again haha

You didnt use the CDX that has the slides on the sides, did you? If so, that could be a problem. Id recheck your solder joints.