I auditioned my speakers for almost 2 weeks. In that time, I never felt listening fatigue once and I was very pleased with the sound. That's how I knew they were the ones I would buy, but I could within a few minutes that I already liked them
I had some Studio 40s back to back with my A/V-2s for almost 2 weeks also, and though I liked them quite a bit, I would notice the brightness after a while too. So the decision was simple.