I just swapped out a pioneer head unit in my cobalt for an alpine. The pioneer was probably 10 years old or so but it was one of the higher end ones (had an lcd screen, fully adjustable eq, sub controls, etc.) but it was starting to have issues. I still have the stock speakers and I've been running an alpine amp and alpine 10" sub in the stock box. I'm writing this at work so I don't have all the model numbers on me. The alpine I put in is the CDE-HD148BT. My problem is that I had the gain set on my amp to a little less than halfway with my pioneer and it had really good bass to it. Now that I've swapped to the Alpine I can turn the gain all the way up and it's still not us "bumpy". And yes I know that gain is a sensitivity adjustment and not a volume knob. The volume control is all the way up on the HU for the sub also. Anyone have any thoughts as to why my bass output is so much lower now? Thanks in advance.

 

pioneer HU probably had a higher volt output on the RCA outputs

 

I wasn't using enough of the volume on the alpine HU (was setting gain for 22 out of 35 on volume control for HU, use 28 or so now).