Speakers for $600.

Quad 12L2s come up under $600 on Audiogon pretty frequently (there were two pair for sale the last time I looked; I don't know the sellers). I have the original 11Ls, which I think are fantastic--fast, detailed, nice imaging, and fun to listen to. I've read numerous similar recommendations of the 12L2s on the forums here.

I second the Spica TC50s, if you understand and can live with their limitations. They don't dig too deep into the bass, they odn't get really loud (although I'd say loud enough), and transient attack may not have the greatest jump factor. But you get supremely evenly balanced tonality across the frequency spectrum, very high resolution, and a natural sense of dynamics within the limits of their volume. One of the most natural sounding speakers ever made, regardless of price. The Angeluses are also excellent. Although I've never heard them, the Spica designer John Bau, felt the TC60s were the best speakers he ever built.

Sequerra Met 7s

My Green Mountain Europas have amazing bass, speed and imaging. Not seem often here but they go for 600 +-
Von Schweikert VR-1 also come to mind

Mobile Fidelity OML-1. Gorgeous and very nice sounding. I agree that the Spica TC-50 are also very nice.