As I posted before, the first time I compared my Denon receiver with and without an amp I thought I heard better bass, more detailed highs, better sound stage etc., just as others have claimed. A few months later I decided to really take the time to do more critical listening comparison, using Stereo CD's only. Thank goodness I only have to deal with 2 channels. Still it was a pain to keep connecting and disconnecting those wires. To my surprise, I came to the conclusion that the 110W X 7 Denon on its own was just as good, even at reference level as the 200W X2 and 350W X 2 amps. I tried all sorts of 2 channel CD's including concertos, symphonies and some bass heavy materials. All my listening tests were done with the Denon set to pure direct mode, without the subwoofer.
I even measured the current with a true rms meter that can measured accurately signals up to a few thousand hertz. The Denon receiver had no trouble delivering the same currents as the amps (I tried two amps) did. That's when I realized I was not immuned to the Placebo effect. I then did a comparison between my two amps. To minimize the time in switching between the two amps, I pushed in the mono button on the 2 channel preamp, and used the balance button to switch between the two amps but with no level matching. To my surprise, this time I was able to hear a subtle difference, but the difference was so small that I was almost certain that I would fail a blind test. Also, while I was confident that I heard a slight difference, I could not say which one sounded better. I would like to believe the more expensive one (3 times more) sounded better though. This test made me think that perhaps the preamp had a significant effect on sound quality.
I am posting some my experience again, in the hope that people may be convinced to accept the fact that not everyone are gifted to hear those often claimed major, huge, day and night difference between amps (power or integrated), receivers, and amps. Moreover, we (I assume I am not the only one) don't just base our comments on published specs, we do based our comments on our listening experience.
In my opinion, if you can hear those difference, good for you, but please recognize the fact that not everyone are gifted the same way. I have no problem accepting your claims, but I hope you would also accept ours. People are going to ask the question "Will I hear a difference/improvements in sound quality.........", or something to that effect. Let's don't assure them they will or will not... They really need to find out for themselves, we can only offer comments based on our own experience.
As an aside, I do like amps, they are usually nicely built, good looking, heavy, and the preamps have buttons to play with. However, I would definitely upgrade my speakers first, before I spend more money on amps. The reason is simple, I have no trouble hearing the difference between speakers, and I know which one sounds better. The B&W 802D comes to mind, time to dream..............