I really like this one! My only gripe is the nearly inaudible bassline? It sounds like this weird low growl far into the background, and I don't really like all that much. I'd expect a more swingy, a tad bit more "in-your-face" bassline, a bit like the kind seen in old-timey jazz songs. But right now it's sortof implied rather than being there. I suppose that's really just a personal gripe though, since clearly the focus of the song is on the two leads.
Speaking of which, I really like how your two leads complement each other. It's sounds like the song was improvised live on a stage, with just an inkling of prep time. The two musicians look at each other, and each do their thing, but working with each other rather than against. The drummer slaps out a rhythm, paying attention to his fellow performers, making fills whenever his bandmates do something spectacular(The bit starting at :38 is quite nice because of that.)
My point is, it feels quite organic in spite of having been made with synths. And that's partly why I like it. It's an eclectic synth-jazz piece with that 3/4 time signature, and those aren't made much these days. It would have been nice if it had been a bit longer I suppose.
As an aside, newgrounds is making your audio skip very much. I don't get the problem when listening to the song on my computer, so I assume it's the websites fault.
that is all.