i think got difference... once i adjust one system's preamp... every knob i play with nothing happens... no changes at all... but mine i can audit the changes to the output as i turn the knobs... so to me... pre-amp if you wan it make sure you get a good quality ones...

as for the price... i think its not how many out put kua... almost all is the same... but the out put voltage and the material used to create the pre-amp...

cheers...