Jarrod,
A JL Audio G6600 would run all that you have plus a low mass sub like a Polk dB or JL Audio W0 or W1. “Under $500” An Alpine PDX5 class D amplifier would be an upgrade in that it has more power to the sub and is nearly 90% efficient. “Under $600”
The Polk dB coaxials will no doubt step up when you run them high-pass and upgrade the power. Your perception may change once adding the amp and sub.
Depending on your tower speakers, we have upgraded many existing pods to HLCD drivers.
Juston
Earmark Marine
marine@earmarkcaraudio.com