I understand what you say perfectly about being confusing. Much depends on things such as room size and speaker efficiency, but I flat out think that outboard amps sound better than those built into the receiver, except in rare instances. I bought my first Dolby Digital receiver around a year and a half ago. I had no idea what I was doing and, because of previously good experiences, thought the new receiver would do the trick. Although I tried to convince myself that I liked the receiver and the sonics of my system, I really wasn't satisfied, despite the fact that I thought it would be a kick ass unit.
Given that my Klipsch speakers are very efficient, I knew it probably wasn't the amount of power the receiver put out, but the quality of power, so I bought a Parasound 1205A amp, despite warnings from some that an outboard amp might not make a huge amount of difference. As soon as I connected, callibrated, and powered up, I was in audio heaven. Sound across all the frequencies sprung to life, dynamic and full of detail, but much warmer than the sonic characteristics of the receiver. Best of all, I noticed that there was less smearing of sound across the soundstage. Sound came from where the instruments were supposed to be and quiet took hold between them.
A few months later, I bought the Rotel 1066, which marked my first full incursion into full separates. This further improved my systems sonics to the point where I no longer felt upgraditis...well, except for my new CD player,a cable here and there, and some minor tinkering with room accoustics and speaker placement, etc. The addition of the pre-pro helped out mostly my two-channel sound, although HT was stepped up also.
As I say, I'm probably through for the time being. The only thing I might even be remotely interested in at this time is perhaps a two channel preamp, but even that is remote. I know there are a lot better systems than mine out there, but I'm personally very happy with mine and it sure beats what I started out with.
By the way, I expect Chu and his minions to come on and dispute everything I've just said, but I will assure him in advance that I did multiple double and triple blind tests each step of the way.
