Thanks a lot to both Neil (the owner of the JM) & to Allan (the very very good guitar player!).
In case you haven't worked out whats happening, Allan is playing over a loop & using an AB box to switch between the Two Crystal & the JM Signature model. Both are being run through a 2x12 cab - the Crystal is using a Crystal cab, the JM is using a custom made Two Rock cab.
I know the Two Rock guys will watch this - please use the comments section below to tell us which amp you think sounds more "Mayery"