I use the foobar2000 equalizer, but if you use Winamp I recommend the Shibatch equalizer. The upper frequencies just need a little boosting, then you keep the amazing natural detail of the card, but get a much needed more airy sound, that opens the natural tone of instruments
Using Winamp, with the Shibatch decoder and Shibatch ASIO output, with 32 bits int out seems to eliminate the plasticky sound. I used to use foobar2000, but got annoyed with its buggy EQ. Can someone else confirm that the plasticky sound goes when they use the same combination?
It must be some sort of incompatibility with foobar2000 and the EMU DSP that causes it. I now get phenomenal sound quality that will easily rival expensive CD players, just by changing the software used. Amazing.
It now sounds exactly like the RMAA graphs suggest, with the highs being slightly louder than the lower notes. My HD595s now sing like a bird