I'm new around here but this is probably better posted in this section:
Amps, Pre-Pros & Receivers
If the concern is whether the HSU will plug into a specific AVR, any of them with a Sub out/LFE option will cover your needs. Pretty much any new AVR will have this option (and much MUCH more). You may want to consider the current EQ configuration available to you that covers sub EQ as well. Not sure if you'll find that for $500 but worth looking!
My advice - get an AVR that sounds good with your speakers (left, center, right, surround) rather than what is highly sought out. Make sure it can grow with you as you dive into this audiophile pool...