Looks like you're having fun -- and that's the most important thing. If you could land some stubby speaker stands on Audiogon or eBay and raise those Polks closer to ear level, that would probably make a big difference as would better positioning.
But the biggest improvement in terms of detail would be to keep an eye out for a nice integrated amp from the likes of NAD, Rotel, Cambridge Audio, Arcam, Cyrus, Rega, Musical Fidelity, Marantz, Denon or other lower-priced brands. For instance, I recently sold my Cambridge Audio Azur 540A that never saw much use in a second system for $175. I've helped others put together systems for even less. I once got a mint Rotel stereo receiver with unused remote on eBay for under $100 shipped. It sounded nearly as good as the integrated amp its circuitry was based on, but for half the price and with the bonus of a free built-in tuner!
So, keep an eye out for a new amp and stands and in the meantime, enjoy what you have. You've done well on a limited budget.
