I doubt differences in amplifiers are audible 99% of the time. I don't doubt that there ARE differences, and that in certain situations we could hear them, but for the most part you can rest assured that your particular amplifier is a good one. I would think that we could only notice when playing at high levels, where one amplifier is straining to keep up with the peaks, whereas a more powerful amp would handle it comfortably.
Denon, Yamaha, Outlaw, HK, Pioneer, Sony, etc.. they are all great quality products and you can't go wrong with any of them. Buy the one that fits the budget, and has the features, power, and looks that is desirable.
I read somewhere about doing blind audio tests in controlled environments and people couldn't tell the difference- at all. In fact, they were allowed to bring their own music so they were listening to their favorite reference material. All the responses garnered from the test(s) (I've heard of two of them like this) showed that noone could tell the difference. All amplifiers were setup perfectly with the same exact sound levels beforehand.
At any rate, all that matters is that you are happy with your purchase. I am VERY happy with my RX-V2400, and would recommend to anyone to buy a Yamaha, also. It has the features I want, looks cool, and sounds great.
