My observation: It's simply not possible to fit all high quality parts and discrete components into an integrated. Take for example high quality capacitors which alone take a lot of space. In separates, you'd be able to use all the big caps you want, but in an integrated you'll probably have to settle with electrolytics in a lot of areas. My c-j phono stage does not have a single electrolytic capacitor, not even in the power supply; this design will not fit into an integrated.