I agree with Seth to a point. I would not settle on the like of the Behringer. On the other hand, I believe once you get to the mid range stuff, I would place in order of importance to sound quality, speakers, source, power amplifier, preamplifier. So yes I would put preamp/prepro last mainly because of the fact that it does not have to the deal with high voltage and heavy current. The power amp has to deal with the same signal but in much higher magnitude where interference, noise, heat all become bigger issues. It also has to power/control all sorts of loudspeakers with a wide range of impedance, sensitivity and efficiency characteristics.