At 11' feet back, you will need a minimum of 150 watts of power to reach *peaks* of 100dB with speakers rated at 86dB sensitivity. I suspect you are attempting to reach continuous volumes of 100dB, with 110dB peaks (concert level). This would require 1500 watts! If you plan on playing at these volume levels, I strongly recommend speakers with a minimum sensitivity of 98dB, + subwoofer.
This isn't a tweeter issue, this is a clipping issue. The tweeter in the 340 is capable of handling just as much power as the NrT dome, actually a bit more - as it has a longer VC. Either you are clipping your receiver/amplifier - or you are reaching the mechanical or thermal limitations of the woofers, thus the frequency response becomes unbalanced and the tweeter response becomes more prevalent.
Sign of clipping... Taking the tweeters out....
?? We have no control over what search engines or what browsers access our forum. Not sure what you are inferring.