Perfection in Newgrounds.
I hate to add another response to your list, but I had to review my favorite song on Newgrounds. :P
When I first pressed play on this piece, I was nervous that it would be the normal thing I hear in the Audio Portal -- a mediocre piano piece.
To my surprise, I ended with what's near the perfect build-up. I've always wanted a piece to actually use something just like you did, and I was, to put it lightly, happy. You did it perfectly -- you had the right mix of every instrument (the piano starting the song -- other instruments coming out and putting the piano in the background).
The song was made to be looped -- it begins and ends quietly, something perfect for a song on Newgrounds. The notes were all crisp, the song was a good volume (I could hear every note), and every piece fits in wonderfully.
This is perfection on Newgrounds -- or as close as I'll come to seeing it.