Matt, I dont think you are being limited at all. You clearly state that the real problem is nodal issues with the base resulting from the geometry of the room and the config of the speaker bass ports. many of the speakers you say have delicious mids and highs, BUT the bass is consistently and issue with anything but sealed, down or front ported.
So yeah, you can improve your source, but that wont change the laws of speaker physics. No matter what the upstream is, you STILL have to find a livable speaker solution, so keep concentrating on that.
This should be particularly reassuring to you, as I threw more speaker options than most at you. LoL