First of all, I don't buy from big box sellers.
More to the point, I'm not an engineer by profession, sensibility or inclination-- I'm an artistic sort who has little interest in why/how a given component works. What I do care about is how it sounds. . . to me. . . in my system. . . in my room. The most reliable strategy I've found for such research is to hear it at home. If demoing gear in this manner disqualifies me from membership in the elite echelons of audiophilia, I really don't care.