The debate started in my life around 1970. Mono, stereo, integrated. I worked in retail and of course this discussion went around and around. Davey O'brien of McIntosh told me that there was no performance difference, but felt that as long as there was a market, manufacturers would cater to it. Saul Marantz made at least one early solid state stereo amp that was actually two mono blocks joined by a face plate (Model 15?). They could be separated and operated separately. Having each amp right next to the speaker it is driving is compelling, at least esthetically. Then there are some integrated amps that make a strong case for putting everything in one chassis. I think especially with the newest Class D amps the integrated approach is quite strong. On the other hand, if you want separates, it is your money, who said this hobby is totally rational?