Driver matching vs break in period


I installed a new mid range driver for my B&W 803 SII and noticed that the image shifted to the speaker with the older driver. I got out my radio shack SLP meter and found that the new mid range driver was about 2-3 DB lower than the old driver in the other speaker. I ended up reinstalling the old driver and putting the new one back in the box. The question is: Is this a matter of matching drivers, or is a matter of allowing the new driver to break in, or is a bad driver? Any thoughts?
koryodell
Did they have the same part number?Also switch them (Midrange drivers)between channels to see if crossover is ok.
I guess I should have said,try the new driver in the good speaker and see if it still has a big loss. I don't think that kind of loss is normal.Make sure the plus and minus are correct also.That my 2ยข
I did switch the "new quiet" driver to the other cabinet and it was still "quieter", so it was not the crossover. I also might have over emphasized image shifting issue, while the image did shift a it was the additional "loudness" that was the main issue. at times, it was almost like having one speaker in the room, especially on vocals. My guess is that the driver might have been well matched with my cross over. Maybe I'll email the B&W representative and ask them what the issue is.
That sounds like a good move.I've had hard,or a little brighter on a couple mids in the past.On woofers,I've had boominess until it broke in.I can't ever remember a quieter one.At least they will know of the problem so you don't get stuck with an unusable driver.