GAS PSP3500.1D repair

OK. I thought you might be doing it to make less noise. If they're in a single enclosure (and the enclosure has a sealed divider separating the subs), you can wire them out of phase to make less noise (working late or cranky neighbors). Dummy loads are better long term. If you need to listen to the amp's output, you can always use a small sub on a limiter.