Hi Brooks, I would like to chime in on this if I may. I currently own the Berning zh270 OTL that has been totally tweeked out, every conceivable upgrade including cryoed outputs, various sets of NOS inputs, cryoed wire ERS and tube dampers. It is a very dynamic amp stock. With the upgrades, the ease, transparency and performance top to bottom is quite good. Especially the low end since it uses a switching power supply. David Berning's designs have always been noted for their low end performance. I have heard the VSM's with 2 of these amps strapped together in my system with the wire upgrade and I must say it was most definitely in the realm of ss control and extension with puffs of air coming from the port of the speaker regularly at moderate listening levels. It literally sounded as though a subwoofer was hooked up to the Merlins but with a coherence that NO sub can project, especially with such a speaker as the VSM. If you are looking at hybrids but love the sound of tubes, I strongly suggest you look into this amp. It is also easy on maintenance since the outputs are auto biased and operate at a very conservative plate voltage relative to their capacity, same with the input/drivers. 20 years tube life can be expected with this design. About as plug and play as you can get without the constant worry of tubes. Another plus is that all the tubes are readily avaliable NOS and are quite inexpensive.
Now having just made a strong case for the Berning I would also STRONGLY recommend you listen to the Joule's per Jim's recommendation. This amp is the most harmonically realistic, natural sounding amp I have heard with these speakers. It is incumbent for anyone purchasing the VSM to hear it first hand. It doesn't have the "plug and play" convenience of the Berning and it also puts out quite a bit more heat but it is a final purchase product especially with this speaker and I can't say enough good things about it including performance, build quality and value. Jud Barber is most definitely a music lover and his designs are masterpieces at reproducing music! The only cavaet is that to realize the bass control that you might get with the Berning I would think that you would have to go with the Marquis 100 monos or the Grand Marquis if you can handle the heat, current draw and price of admission.
Before purchasing either I would try to search out both for a listen. I doubt any hybrid out there will offer the musical involvement these two do with the VSM but on the other hand there are many tube designs that work well with the Merlins. On the SS front I would look at the Sims and Belles that would probably offer much of what you might expect from a hybrid.