I was realy speaking in general terms of OTL designes. In particular the protection and auto-bias circuits are implemented either using tubes or transistors depending on model. Amps that are pure tube-OTL with all implemented protection basically overwent tough reliability issues but "naked" tubes still drop the power twice when impedance drops twice and that's in the nature of all "naked" tubes.
OTLs can realy be used successfully in bi-amp applied for active systems where there is no need for higher power i.e. for freequencies from .8k to 20k and that's where most of our ears hear the best clarity resolution.
OTLs can realy be used successfully in bi-amp applied for active systems where there is no need for higher power i.e. for freequencies from .8k to 20k and that's where most of our ears hear the best clarity resolution.