I have a quite old Alpine head unit that has a tape adapter, and I have 2 MTX Terminator Subwoofers hooked up with a 400 watt peak power MTX terminator amp that came in a package with the subs. My subs are barely hitting and a very quiet, and I was thinking that it may be my old head unit and the tape adapter im using that are cutting down on quality of sound and making my subwoofers quiet. Help please