BAT VK 55 SE

I have the standard VK55 not the SE, same power rating though.  I previously owned two other amps which offered switchable triode operation.  In both cases triode sounded lackluster, curtailed bass, soft treble, limited dynamics, basically no contest compared to ultra linear for which those amps were primarily designed for.  I purchased the VK55 to hear what a true triode amp sounded like.  It doesn’t possess any similarities to the switchable triode amps.  It is dynamic, great bass, highs not muted, and non fatiguing.
Pros:
Great sounding amp using 91db 8 ohm speakers 
Doubles as a room heater in the winter.
Fuse blows when an output tube goes south without any damage to the amp.


Negatives:
Not the prettiest looking amp.
Doubles as a room heater in the summer.
Must use a balanced preamp.
Output tubes a bit pricey.

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.