How to evaluate amps that are not broken in?

Break in is something that is highly debatable. Considering all of the variables that are at work EACH time you sit down and listen it is very difficult to attribute any gains directly to break in.

However, people that do believe in the theory seem to agree that only good things come the more the component is played.

I agree with musicslug that the components will only sound better over time as the components within the gear start to break in and stablize.
If you have only 2 days over the weekend I would let the gear play continously for a set period of time and then start to listen seriously;at least let the gear thermally stabilze.
Enjoy!!

Robr45, I experienced a dramatic change with my Creek 5350 se-- far beyond what I was expecting, actually. So I guess that experience puts me firmly in the "believer" camp. Rleff, I will do as you suggest. Thanks!

Doesn't it seem odd that "break in" always seems to result in an improvement, never a change for the worse?

Whoaru99, very interesting point. I was thinking the same thing as I was reading the responses. I can imagine a situation where a component sounds wonderful and a change may not be perceived as better. Hmmm.
The only new component I've purchased lately is an Oppo DV-980H but I only bought it to use as a transport and I haven't noticed any changes. I have trouble thinking the data stream will change much over time.