Are these things really using a Tube gain stage in each preamp? I think some have 8 channels. Even one gain stage per channel would mean four 12ax7s.

Is this the case?

I'm skeptical, like you seem to be.

I think only the first 2 combo-jack "superchannels" are tube-equipped, and they are a single mil-style 12AX7 tube application. The intent is to dial in a little saturation, according to the documentation. This leads me to suspect a starved-plate design (unconfirmed).

I do not own this gear. Your post got me curious, and I did a brief search.

If it IS, in fact, starved-plate, that would negate any further interest for me.
I still have a few starved designs that remain in use, but certainly not for the "toobs". Their solid-state hardware preamplification remains very useful, to me. The humble Studio Projects VTB's and Aphex 107/207's come to mind. On these units, I ignore the tube function, entirely, but that's just me...

Best,
Frank

There were only 2 preamped channels. With tubes. Pretty sure they were starved plate.

What does starved plate mean?... nevermind I used chat gpt for the answer

For posterity, starved plate refers to a vacuum tube operating well under it's originally intended supply voltage.

In conventional (orthodox?) Tube applications, the voltages typically supplied to the tubes are in excess of 150 volts. That's not an official cutoff voltage by definition. I'm just throwing it out there as (hopefully) close.

Real tube gear uses voltages that exceed typical wall-wart capabilities. Additionally, the audio usually runs through the tube in a full-plate design. The starved-plate designs just tap some distortion off the starved tube and mix it in (parallel) for a bit of "toob warmth". The actual audio amplification is provided via solid state circuitry.

I know it seems counterintuitive to those seeking that toob "warmth" (distortion), but tubes were once THE answer for "clean".

Tubes weren't just the answer for clean... tubes were at one point the only answer to audio amplification period. The transitor was invented in the late 1940s but didn't see much practical use until the 1960s

Indeed most older recordings were going for as clean and as much headroom as possible with the gear they had at the time. Except of course when they weren't.