CJ MF 2500A:is it gonna open up?

I had the same experience with a new 2500A a few years ago. Very disappointing at first--lots of detail, but metallic-sounding, as you describe. I've been through this before, so I used a technique which had helped me in the past: over the next few weeks I experimented with power cords, power conditioners, cabling, isolation devices. Naturally, everything I tried changed the sound, and often for the better. As I listened for combinations that worked, my point of reference began to change, and the superb detail and ease of the 2500A began to work its magic on me. I grew to love the amp, and kept it for over a year (a long time for me). What happened? The amp broke in, my ears broke in. The idea here is to focus on something other than just your amp (and your disappointment). Meet the amp halfway: start playing with other things in your system to see how they can enhance the "new sound" you're hearing--I'd bet you'll come to a happy accomodation soon.