I have had a pair of Joe's "improved" earpads for a couple of weeks. I thought I would post a little information for anyone who may be interested.
As far as how they sound, simply put, consider getting two pair. The HP1000 is soooo dependent upon the earpads. The replacement ones offered by TTVJ change the character of the headphones where it seems the sound is dulled possibly by mostly effecting the upper and mid upper range. The bottom end was also not very tight. While I am no expert I am guessing they are just too dense. They are not a great direct replacement the originals.
Joe's "improved" new pads do the trick and give new and sustained life to the HP1000 series. I compared them to the the original and TTVJ pads on my HP2i. Overall, the new pads attenuated the sound a little bit compared to the originals but sound at all frequencies were definitely improved. These earpads, for which Joe devised some process to allow more sound to flow from the drivers to the listener's ear, allows improved resolution at all frequencies, work very well and are an improvement even over the original pads. Any HP1000 owner should seriously consider getting them as no other earpad, including the original, sounds as good. Also, they nicely improve the sound on the SR225 and I suspect some other Grado headphones. Joe has done it again. Hopefully, some others will be able to chime in on these once they try them out. It is money well spent IMHO.
Joe is selling them for $150/pair. You can contact him directly at: 1-803-324-9768.
In the interest of Full Disclosure: I am a personal friend of Joe but am confident in my impression of the new earpads.