I have 2 of the older version of that.
View attachment 111781
Never tried the tuner out to a third amp...

Dammit, I might need more amps.
That's what i used for the channel separation on my 'mini-EJ' rig:
clean side was 2 blackface Vibro Champs running in stereo off of an old Korg PME-40x modular multifx unit (digital delay, chorus, overdrive, and a graphic eq), and the dirty deed was done dirt cheap with an El Mo, a Wampler Tweed '55/Euphoria stack, and a Carbon Copy into a 1st gen. UK-built Marshall Class 5, sometimes augmented with a stand-alone Fender Reverb Tank.
That was the final iteration before i decided to go ampless.
i was trying to post a pic of that setup, but ...

... if even the file is 'too large' that ought to tell you something, LOL!
NGL, it sounded glorious, that setup did; once it was all connected properly, trouble shot thoroughly before the actual use (but not too much before), and left on and baby sat to make sure nothing changed in the interim.
Too much time and stress for me; in the end i'm 90% of the way to where i want to be sonically with just this:
Like so:
Combining that simple setup with just a couple of guitars (including the
.strandberg* Boden Metal 8) and basses, and the ROLI NOISE app on my phone into a Scarlett 2i2 and from there into Logic, i was able to produce this album:
YMMV, ofc.