An interesting article with even more interesting comments.

"Marshall had been one of the few amp makers left to embrace digital modeling (its JMD:1 series of modeling amps still made use of tubes in both the preamp and power amp), but the march of progress finally caught. Marshall has released the $199 Marshall "Plexi" Super Lead plugin, the first and only software modeling plugin to bear the company name."

http://arstechnica.com/gadgets/2015/04/marshall-goes-digital-with-its-first-official-software-amplifier/