The IR I used in the Brit Silver clip as well as the Slash-inspired AFD and UYI Mixes are from the York Audio MRSH 412 MV30-Dual pack (
www.yorkaudio.co).
The story behind the JCM Slash, as I've read, is that Slash needed more Jubilees on the road and asked Marshall to make some for him. They were only able to source enough original Jubilee components to make 3,000 units. Since it couldn't be mass produced, Marshall released them as a limited edition and their first signature amp model in '96 and '97.
The one I have is extra special to me. I got to play one when I was 14 at Sam's Music here in Nashville and have wanted one ever since. 25 years later, my friend tells me her husband has a Marshall Slash amp he doesn't play anymore. I go to his house to buy it and find a "Sam's Music" sticker on the back. Any store lucky enough to get a JCM Slash could only have one unit, so the one I have is THE amp I played when I was 14!
Check out the Jubilee preset I posted and you'll get a great feel for the amp. Raise the Master Volume a touch if you want more mids and a little less sizzle (that knob has A TON of tonal shaping quality).
The preset matches my amp through a Fractal LB-2 load box, so feel free to change the impedance curve and set Speaker Drive, Speaker Compression, and Speaker Thump where you like them.