Do amps have a sweet spot?

In most any practical sense, yes, it may be normal, especially for lower-priced gear, to have that portion of its volume range that seems to open up a bit better...although exactly which portion that may be could possibly be different in different systems. In one system the amp could sound better at 3/4 of its output and yet in another system sound better at 1/2. Usually when you start moving up the food chain and start buying better and better components, this sort of thing becomes less and less apparent and vol. and dynamics start to become more "linear" (as do power supplies). By the time you've done that, and/or have gone successfully enough down the power-conditioning road and perhaps have also looked into things like how much your vol. control is veiling the sound, being somewhat picky about interconnects for your own app and even about things like grounding issues, what you can end up with is an extraordinarily linear rig...although all that typically comes with the price tag as well, of course. But, if you did all that, the I believe the surprising part to me is that even your current gear would pass that kind of test with flying colors, giving absolutely ideal performance, no matter what the vol., right up to clipping. So the real answer is that, yes, you do have any given amp's tendency to sound better at whatever point it will, but, that characteristic is in no way inherent to the amp itself, and, in the long run at any rate, there are those things I mention that you can look into to improve the situation. All this that I'm talking about here is apart from the ins and outs of matching your amp to the right speakers and so forth, which could at least influence things. Hope this helps.

The simple answer to your question is yes. Its very possible that your amp will sound better when you push it. I differ a bit with Ivan, though, in that you can have the same issue with very expensive components. It all comes down to system matching. Also, with newer components, its not the issue it once was. Your Aragon is a pretty old unit. Newer designs, are less prone to have this problem. If you liked the NAD, try the next model up. It sounds like you need just a little more power than the model you heard.

Let me add that some speakers sound better at higher volume as well.

Thanks guys. At least, I now know that I may not be crazy.

I really can't explain the love affair that I'm having with this Aragon. I do know that it's really OLD and out dated. I suppose there's just something to a two channel 100 wpc amp weighing 40lbs.

Still, I did like what I was hearing out of that newer NAD model. My dilemma (isn't there always one of these?) is that NAD's top of the line classic unit is $1500. I really don't need a pre amp. Mine is a NAD C162 and is pretty nice. My dilemma is what sort of amp to go with. I've been very interested in the Class D offerings. I also have to decide how much power it is that I really need.

Anyway, thanks a lot for the comments.