i have a 1995 custom shop green tolex prosonic and i love it...it absolutely sings. there is a switch in the back to change from a class a to an a-b or even all solid state. the eq is active so you have to be careful with your settings as it alters the volume. this is fenders answer to the mesa just to give you an idea...but it has that classic fender reverb clean tone as well. i use it for blues and i'm going to be cutting some rock tracks with it this week (broken elbow and all...) so i'll see how she sounds in that situation. i'm a marshall fan as well so trading your jcm900 is up to you but i think you will be happy with the prosonic if you get it. to me its more versatile than the jcm900. good luck
