I figured I'd let the people in this thread know that I posted a long-term review of the HA-S500 that I have owned for nearly three years now:
http://www.head-fi.org/products/jvc-victor-head-band-portable-headphones-ha-s500-b-black-japanese-import/reviews/15579
If you happen to read it, please let me know if I made any technical mistakes when describing the sound characteristics.
Read it; thanks! I'm not qualified enough to help you improve it, but I listened along with you and compared my impressions with yours on the HA-S500. Hopefully, others will provide more enlightening response.