You may or may not have heard of the Synergy modules and amps... but IMO it's quite a game changer and very unique in the gear market. While modules have been around for a bit, these are different. Basically, this allows you to turn your existing amp into an entirely different amp, or variety of amps by implementing the module idea in a whole different way. It also allows you to take an all-tube high voltage preamp with you to a gig where you may not be able to drag an amp of your choice.
While I didn't go into every little aspect of the Synergy units, I did want to show you what I am going to use it for personally myself, which is take my favorite single channel amp and give it a variety of all tube overdrive and distortion channels, that reacts just exactly as if it was built into the amp. So rather than mimicking the sound of a plexi through a combo, why not actually turn it into a plexi at the push of a stompswitch?
Check out Synergy here:
http://synergyamps.com/
For a VERY in-depth review of the Synergy stuff, check out Hennings videos:
https://www.youtube.com/watch?v=UtS5md6KZlM