If you're going to mod your DH-500 yourself, I highly recommend The POOGE Chronicles. They outline modding in general, and the DH-200 specifically, along with a number of other pieces. The principles they use could be applied to anything you were modding, and cover both the theory and the implementation. I bought my copy here:
http://www.audioxpress.com/bksprods/books/bkaa25.htm
Well worth the price.
David
http://www.audioxpress.com/bksprods/books/bkaa25.htm
Well worth the price.
David