I never played a gig sitting, because then no one in the crowd would stand up and dance. On the other side - i think it's normal for guitarist or bassist to play sitting, according to his health problems. It can be quickly explained to the crowd when starting the gig by vocalist.
At home i use my Aguilar tone hammer 500 for the tone i want, with a volume down, from balanced output to focusrite scarlett 2i2 then to my pc (samples and recording) and use headphones from scarlet for hearing what i am doing.