I prefer not to use file upload sites (since they wont allow upload/download with javascript disabled, and often have ads etc with malware attacks in them) but ill be happy to dcc it via irc or whatnot.
The .ash file isnt music, its the audiosurf track associated with the song. Using the same .ash ensures everyone competing has identical block layouts, length etc. The .ash file should be placed in audiosurf/engine/audiosurfhc.
Also, i tried Nighthawk22 - Alternate Dimension and got 585 traffic, but it was surprisingly easy for its density (first run stealth), with most of the blocks being long chains of colors and minimal grey dodging needed. Interesting nonetheless; its the highest traffic unmodified, actual music track ive seen to date.