Nuvista Tubes - General

Of course there are direct coupled tube amps. The Loftin-White instrumentation amps, designed in 1929, and still used today, were direct coupled designs. The Acrosound Stereo 20-20, designed by the brilliant Ed Laurent, only has an input coupling cap

" The Acrosound Stereo 20-20, designed by the brilliant Ed Laurent, only has an input coupling cap"

This technically should not then be called a direct coupled amp. As there is a cap in the signal path.
It should be described as a capacitor coupled amp with direct coupled output stage.

PS: But wait it’s not even that, it has an output transformer as well, so it has transformer coupled output as well. So in no way can this be called a direct coupled tube amp.

http://www.cma4ch.org/chemo/image/hifi/acrosound-stereo-20-mod-r.jpg

http://2.bp.blogspot.com/-AuRjf-5iXM8/UEYcDrM6X8I/AAAAAAAAAew/RixShlEJghU/s1600/Acrosound_20_20_sche...

Cheers George

George, please correct me if I am misquoting you - in which case the circuit is no longer pure tube, but hybrid.

Correct, as I was letting the OP know that the final sound signature of it was solid state and not tube.
If it didn’t have the solid state buffer, the sound would be very different and not be able to drive very well either due to high impedance, that why Anthony Michaelson (MF) put the solid state output buffer in it.

Here is a pic of the output section.
https://ibb.co/nvT2sR

Cheers George

I also don’t really see DC coupling as a benefit in an amp

That's your opinion, listen to a good direct coupled amp, say Gryphon/Krell ect, then listen to it with the best cap or transformer you can get inserted somewhere in the signal path.

For the most transparent sound, the best cap is no cap, and the best transformer is no transformer.

Cheers George