BAT VK 55 SE

Ok. Those output tubes really have my interest. I'm not a tube guy. MIG Jet fighter tubes? That can withstand EMP from a nuclear blast?  This is stuff of legend. 

Yeah, the MIG history sounds cool, but it's not the reason to buy or not. The 6C33 is a reliable tube type and has been used as the primary output tube since BAT began. They are long-lasting when used in a BAT amp thanks to their auto-biasing. 
Sonically, this type of tube is a good choice for those looking for something between the sweetness of lower power triode amps (e.g. 300Bs) and the more rockin' brute force often associated with high power tube amps using 6550s, EL34s, etc. 
The 6H30 "supertubes" are highly regarded and also reliable. They are a newer design vs. many small signal tubes, and therefore don't offer many options if you want to experiment with tube rolling, but that usually is more of a factor when used in a preamp. 
The 6SN7s otoh, are available in many brands/variants should you get the itch to play around. 
Overall, the capacitor upgrade of the SE probably makes a noticeable improvement, but I haven't heard the two side-by-side to compare. 
Having previously owned the earlier VK60 and later the VK150SE monoblocks, FWIW, I found BAT power amps great performers with approriately matched gear. Service/support from Viktor and team in Delaware were exemplary, even if their replacement tube pricing is no bargain. 
If you're buying used, this amp has been around a long while, I'd consider checking the serial# and confirming manufacturing date and take that into consideration for pricing. 
Cheers,
Spencer  

I took a regular VK 55 home to audition. My speakers are 4 ohm so I hooked them up to the 3 to 4 ohm taps on the BAT. There was a channel imbalance, one channel was weaker than the other. I hooked up the 4 to 6 ohm taps and the channel imbalance got better. Must be something wrong with the amp, bad caps or transformer. The tubes are new. I'm going to try the SE version and see if it works. 

I personally have not lived with the BAT amps in my home or system but do have a friend that runs them in a near identical system as mine powering a pair of Wilson Sophias and they are marvelous amps, he actually had them wired to mono blocks doubling the power, which I felt was not needed. He has had them for probably 8 years with no issues at all. BTW, my amps in my system were MB125s with about the same power rating as his 55s after wired to mono.
 

tooblue, The dealer that I am possibly getting the BAT from is also a VTL dealer.  I used to work for the dealer so I get 25 percent off retail. Wonder I should go VTL ST 150 instead of the BAT?