Alan, are you talking about what seems like 'hiss' in the track?

I think there may be a string or 'aaahh' type pad in the backing track that has some higher end bits to it that may sound like hiss.

If you apply a 'noise reduction filter' to this backing track (which is what I would suggest you try first if you go messing with one), then much of the sparkle of the backing track will be lost - plain and simple.

I do hear some noise at the very end of the .mp3 file. You play a final chord - guitar only, and I hear some delay going and some reverb, and then just in general - fuzzy hiss right before the .mp3 cuts off.

That seems to be your guitar in isolation - I don't hear any of the backing track remaining. If it is there, it is so low in volume that you could quickly fade it out underneath that last guitar strum and remove whatever hiss is possibly there in the backing track.

What does listening to the backing track by itself sound like?

By the way - because of 4 Shared's little flash animation advertisements, I'm unable to listen to the 2nd file. I had my in-ear monitors in to listen to the .mp3 file in detail in isoloation. When I clicked your 2nd link, I nearly jumped out of my seat because the flash animation built-in to the 4shared site was so loud. I've got to let my hearing recover!

If you are asking people to listen to songs of yours, I would highly recommend finding a file sharing site that does not have this issue.

-Scott