Well maybe I'm like the guy whose only tool is a hammer, so to him every problem looks like a nail...
I tend to see loudspeaker radiation pattern issues behind this sort of problem. Briefly, in this case the tweeter has a very wide pattern in the crossover region and the woofer has a fairly narrow pattern. So if the response is "flat" on-axis through the crossover region, off-axis (in the reverberant field) you may have 6 dB more lower treble energy due to the tweeter's wide pattern. This will skew the tonal balance in a semi-reverberant environment, such as most home listening rooms. A thick felt pad around the tweeter would be my suggestion. Here's a link to a company that makes excellent ones; their product will also lower coloration and improve the imaging:
http://www.diffractionbegone.com/
One other thing that might be worth investigating is enclosure tilt. My recollection is that the Epos has a gentle-slope crossover, which says to me that there may be a null in the crossover region either above or below the tweeter axis. Try listening with your ears higher or lower and see if that helps. If you find a height where the brightness is minimized, find a way to tilt the speakers back so that the same relative angle with your ears is duplicated at the listening position. I have no idea whether this will actually work, but as far as tweaks go the price is right.
Duke
dealer/manufacturer
