running below the RMS?

Sure, run em under RMS.  Don’t run the amp to clipping.  If you think you need more volume out of the subs, get a bigger amp.  There is no danger to your amp as long as you run it in a stable configuration (if its 4 ohm stable bridged, don’t run it at 2 ohm-duh!).  You might be doing yourself injustice by running the subs far below the RMS rating, but if your within say 75% of the RMS, then I would not be compelled to run out and find one that matches it, your probably getting a good bit of maximum out of them.  Meaning if your speakers are rated at 300 watts, 300 x .75 = 225.  If your running at 225 or better, you would probably not notice a huge bump in volume or clarity by running out to get a 300 watt amp.  Though, all things being equal, it would not be fair to compare the wattage coming from a Audiovox amp to that of any highend amp.