A long-time client of mine has been letting me tinker with his JVC's and I've finally almost finished the cups and re-cable. I obviously haven't applied a finish coat to them and the cable still needs some tidying up, but I wanted them up and running to audition them. And I gotta say, I'm very, very pleased with the well rounded, transparent and wide soundstage. They just do alot of the frequency very well. Checked them out with my worst offending album, Ray Lamontagne-Gossip in the Grain which is awfully sibilant and harsh. The JVC's are near flawless with that album.
The cups are few centimeters deeper than the stock cups and they are much more dense. I'll try to post the inside of my cups compared to the stock cups in the next day or so, but there is a pretty visible difference in construction and it is paying off in spades.
Not a ton of slam, but again, so well rounded to my ears. I'll need to keep listening for a few days.
I may actually be dying these black or perhaps grey or a nice vivid brown if the client wants, but I really think they have a very unique look with one completely bare cup and the other with a singlular crack of lighting running through the bottom.