I had the same experience changing power amps. I believe you will have an initial impression right out of the box. If you're not "neutral" right out of the box, break-in won't move you to positive. Just my experience. Moving from tubes to SS is difficult for most. I know it was for me. Just saying.
In the end I did move out of tube power amps (because of cost & heat) but ended up adding a tube pre back in the chain.
Trust your ears!!!