IMHO, the "separates are always better" mantra is at least 30 years out of date. Two advantages:
Value for money: you're not paying for interconnects, another power cord, another chassis, and more packaging (it's amazing how much the latter two account for the wholesale price, especially at lower price levels).
Performance: I believe that lot of what makes a system more "alive"-sounding comes from lowering the noise floor. Bad grounding and impedance mis-matches play havoc here; an integrated eliminates pre/power interaction problems by construction.
Advantages of separates include automatically separate power supplies and easier shielding, but in my experience skilled designers can now make integrateds competitive with separates at prices well into five figures.
