I have a stock CD player, 2 12" 900max/300rms xplod subs and an Alpine amp putting out 400wrms to each sub. I was told I need an aftermarket headunit. I was hoping to spend less than $150 online/on ebay for it and had 3 main options.
#1. Pioneer 4700 (only disadvantage is the 2.2v outputs) #2. Panasonic CQ-C8301U (ADVANTAGE is it has 3, 5v outputs) #3. Anything else much better than those that you can think of for that price or less.
If your stock head unit doesn't have RCA outs you can get a loc to make it work. If the Alpine amp has high inputs you can use them. You say 400 watts RMS to each sub or 400 watts RMS to both subs. Is your amp running two channel or bridged with both subs?