i'm not sure about axiom's,but many 'mid to high' end speakers have protection for the tweeters(i guess mids are possible) that are basically light bulbs that drain off excessive power to protect the drivers.i'm not sure but it's possible that's what you are hearing in the 'balance' of your speakers.
quick test,back off the treble on the 950,listen combfortably,then start to turn it up,see if the sound stays uniform.now it's possible that with the reduction in the treble circuit,the louder you go,you may get some tweeter gain at higher levels.it's possible you've reached the limit of the tweeters and the x-overs are trying to protect them,which can get annoying but it's better than replacing tweeters or getting up to reset the breaker(which i had to do with my d-9's years ago)