Paralleling Outputs of Audio Research VT100

Kinda crazy. I think it should work. I have two VT100 amplifiers I use as bi-amped mono blocks. It was a big improvement adding the second one but I think I really need more power. I was thinking of paralleling the outputs and using the 16 ohm taps to drive 8 ohms speakers. This should give an 8 ohm output drive but with sqrt2 more output voltage. Looking at the VT100 schematics the center-tap of the output (4ohm tap) is at ground and the 16 and 0 outputs have a fully differential output swing. Doing what I propose should put all of the actual signal in the feedback too. The 16ohm and 0 ohm taps are where the feedback comes from. Anyone done this? Before anyone flames me I am an analog circuit designer for a large semiconductor manufacturer and have a load of patents in circuit design. The highish output impedance should save any current sharing issue. It will work and the math is right I am asking if anyone has done this before.
I haven't done anything like that, but it sounds like you have thought it through knowledgeably and well. I assume from your post, btw, that your version of the VT100 has a 16 ohm tap, as the photos and schematic here show only 4 and 8 ohm taps.

The one question mark in my mind about doing that would be what would happen if while music is playing a failure were to occur somewhere in the signal path in one of the two paralleled channels, resulting in that channel attempting to output zero volts while the other channel is attempting to output a full amplitude signal. As with many ARC amps the output impedance of the VT100 is not all that high for a tube amp (at the ARC DB page I linked to above it states "output regulation: approximately 0.8dB 8 ohm load to open circuit"), and I would have some concern about the possibility of damage in that situation.

In any event, good luck, and welcome to Audiogon! Regards,
-- Al