How do you listen to new components?

It's a good topic. Needs a bit of spelling out.

I assume you're talking about comparing a new component with an existing component? Or do you mean two components you've never heard before? Is your interest in the decision process for making a purchase? Say a little more.

Some years ago, a friend let me try some of his isolation devices. I placed them under the CDP and thought, Meh.. doesn’t sound any different.. Months went by and I forgot about them, until he asked for them back. Once I removed them from the system, I instantly noticed the change.. while still subtle, it was evident..
Recently I upgraded my DAC with a new USB interface. When I first Plugged it in, cold and all, I could instantly hear the difference.. So it can work both ways... So many variables.. Mostly, I need some time to fully comprehend differences.