Triaxis is an amazing animal. And the eight modes change more than just the EQ between the tube stages.
It uses relays to rearrange sections of the circuit into different preamps.
Some modes have the tone stack after tube gain, others have it in front.
I'm pretty sure the Recto board's Mids control is actually at a different place in the circuit than the Bass & Treble controls.
One weird thing that takes getting used to is that the Presence control in a Tri is dynamically responsive.
Sounds great, right? But it can be very counterintuitive since doesn't behave at all like the Presence knob in amps.
Setting the Presence higher makes it darker to begin with, and then it gets brighter the harder you play.
Turning the Presence low actually makes the tone brighter except when you pick harder.
I think this caused many who tried one out back in the day to decide it's freaky and hard to control.
Still, it's very handy once you get the hang of it.
IMO Mesa shouldn't have called this a Presence control in the first place. It's too different.
They should've labeled it 'Dynamic Voice,' and labeled the graphic-presets control what it is, EQ.
There is one hardware weakness in these, too: the front panel membrane controls have been known to wear out on some units.
But it's been the heart of my tone for four decades, and the only annoying issue I had was a persistent ticking sound.
Turned out that was caused by having a WiFi router too close to it.
I've got some basic pedalboard-&-amp rigs too, originally for pickup gigs, the odd jam, or sessions where I wouldn't be using the rack.
More recently I've been going old school; haven't actually gigged the rack rig in several years now.
I still love the Triaxis, of course.
But these days I mostly use one of the pedalboards into my Friedman (or sometimes into a blackface Fender, depending).
It's an easy - and lightweight - way to go.
Has me doing the pedal dance again, though. And I'm not as light on my feet as I was in the 20th century.
Got spoiled running MIDI presets for all those years...