You bring some good points, but in real life, from an engineering perspective, integrated systems have much better odds of sounding better than matching separates unless they have been specifically designed to work together ( and then it defeats the purpose of going seperate, it's still a "system") really I see people buying very expensive equipment, and because you have a good preamp, a good Dac and a good amp, put all tree together and in more case than not 3 perfectly fine components will end up a crappy system. That's because still today, there are no solid standards in input and output impedance, in output voltage in phase response under load, etc. ok people use quick and easy impedance matching formulas but there is more than that. If an engineer work out it's signal path from start to finish, very rarely a consumer can do better. The lines are blurry now. Most DACs have the equivalent of a preamp at their output. They don't call it that they'll say "2 Volts output" or something like that. Do you know what the optimal voltage for inputing this amp is? I don't, specs don't say it neither. So do you know for sure what is better between directly connecting your DAC or go trough a preamp section? Depend which DAC maybe?I I don't know, and I'm an engineer designing audio products, asking the consumer to make these choices are likely not a good thing.