Only the Tone, Dynamics and Reverb do. You might be looking for a dual-amp setup as opposed to a master-slave setup. For that, you will need to run a splitter before the amps, and all the effects in the loop should be stereo.
Hi Petar thanks for your answer. I actual found the Laney IRT 60/120 manual which is a little more elaborate about the signal path. it seems that you are correct and the effects loop is right before the reverb, then tone/dynamics control come in place. For 60/120 the wattage, i would guess, could work as kinda master volume control, but for IRT studio we only have a switch on the input.
what i was looking is to see if i could occasionally skip the preamp loop. I have digitech RP360XP that i plan to put in front of the Laney preamp and use basically as a set of stompboxes (compressor,distortion, volume/wah swtichable, occasionally envelope filter or whammy), but i would in rare cases want to use the digitech amp modeling (like fender tweed amp or something like that).