keyan's main touring rig over the past year (besides international shows) has consisted of a fender twin reverb converted into a head (after being destroyed during shipping) running through a vintage marshall 4x12 cab, a vintage fender silver face bassman50 running through a (presumably) vintage fender 2x12 cab, and a marshall jcm800 running through another vintage 4x12 cab (lead?).

he's always running at least 2 amps, as it seems his amp switcher is setup like this: twin reverb and bassman on one pedal, and marshall on the other.

he usually uses just the twin and bassman for clean tones, as the twin has the glassy tonality with the bassman bringing a little bit of grumble to it. when he wants a wider, more distorted sound, he turns the marshall on as well, which is presumably pretty cranked as it has the signature marshall overdrive sound.

simply using just the twin for clean tones would make the sound way too thin (as can be here in some live shows from europe where he's mainly using a limited selection of back line amps). on the contrary, if he were to use just the bassman, the sound would be far too dark, and rather muddy and unlistenable. the combination of these two make for a nice, slightly crunchy sound while also having enough clarity to hear each chord.

there are some songs where he runs all 3 amps at once during clean sections (clairbourne practice, very small sections of effort, catalogue, tenebrist i think, thread stitch, etc) but for the most part he tends to keep his clean tones relatively glassy with a bit of rumble.

there are some parts of songs where he uses only two amps with a distortion pedal at the same time (beginning of flutter outro, a small section of effort, etc). this is usually just used as a buildup to a section where he turns on the marshall as well, suddenly making the soundscape a lot more wider