Driving 1 ohm

Rwwear, ESLs do not respond well if the amplifier can double its power as impedance is cut in half. It will result in no bass and too much highs. This is why tube amplifiers are often preferred for ESLs, despite the misguided attempts of several ESL manufacturers of making the speaker's impedance really low in an attempt to make them work better with transistors. The result is often a speaker that neither tubes nor transistors can actually make sound right.

For speakers like this tubes and a set of ZEROs are usually the best solution. See

http://www.zeroimpedance.com
and
http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.

Rwwear, in the real world, people want to use OTLs with low impedance speakers. If you use an autoformer to do this, you often meet with success. The fact of the matter is that the autoformer has bandwidth that is wider than most amps, tube or solid state, which is only possible because its turns ratio is so low.

IOW, using the ZERO would not be practical if you did not already have a low output impedance and no DC at the output. So that could be an OTL, but it could also be a transistor amp. Its already been shown that a transistor amp will sound better driving 4 ohms or less if it does so through a set of ZEROs rather than direct.

So the argument holds regardless of the amplifier technology, which inherently includes OTLs.

The Scintilla does not need a lot of power. We drove it very easily with a set of MA-1s and a set of our Z Music autoformers (we no longer make that product, but something similar is sold under the name ZERO). Its not normally a load that you would put on a tube amp but it worked great!