I guess it would depend on how deep or thick the speakers are. I have a Canton Set 400 (old, but awesome speakers) which has a pretty hefty 6 1/2" woofer with a mounting depth of about 3 1/2" deep, and it fit fine with a little room to spare. So, with careful measurement, and centering the magnet of the 6x9 with the deepest area of the cutout, you should be able to fit a good quality pair of 6x9's with no problem. I guess if they are too deep, you could use a spacer ring to get the depth needed. Just remember:measure twice, measure again, then cut