I'll weigh in that you are on the right track if better fidelity is your ultimate goal. Generally speaking a good set of separates should move you in that direction.
I've always been a big fan of receivers for their ease of use and compact size. I have several integrated receivers in the house including an original Sansui 9090db which powers my Algonguins and a Harmon Kardon AVR80. Both have the usual great FR, distortion specs etc.
However for serious listening I rely on my Integra AVR9.8/Outlaw 770 combo and my Pass Lab B1 buffer pre/McIntosh amps. Soundstage width and depth as well as imaging are just better with quality separates particularly if you like to listen for long periods. The reasons for this are fairly well documented.
Based on my experience, heat and quality of circuits and internal power supplies are the items which most determine why these differences exist. Heat plays havoc with specs and leads to a drop in sound quality of the unit. With a receiver no matter how good its designed its not going to have less heat than a system with separate external amps. The other factor hurting performance is the amount of RF emanating from the internal power supply and how well its isolated from the rest of the circuitry. Modern integrated processors have actually really improved in this area but again it depends on how well the internal amp and other transformers are insulated.
As usual there are exceptions. With all the advances in audio engineering the decision is tougher if the choice is between a high end receiver and lower quality separates. Also with separates, component matching and system synergy is also a factor to be aware of though its less of a concern with an all solid state setup.
