Stick with Aerial 20T to play above 100Hz? Or MBL?

Also been thinking of replacing monos with two stereoamps for biamping. I can then send the high pass filtered signal from my subs to one channel on each stereo amp which will amplify the bass for my 20Ts, and send full range signal (not filtered for ultimate sound quality) to the other channel that will go to the head unit of the 20Ts for midrange and treble. Or is it best that this channel doesn´t see the below 100Hz information as well?

Cappuccino, some good suggestions and speaker options, regarding what Jallen said about the MBL 111F's "the sound flat if only playing at a modest level. They sound best with their ears folded back and cranking it out"

I disagree with that comment, that's another issue but nothing to do with the speakers them selves, most likely what was feeding them.

Your room has standing waves which are causing a bass mode in the region you have defined. You have two options 1) fix the room or 2) buy speakers with a built in equalizer or purchase a stand alone room equalizer such as the PARC to use with the 20T. Both aforementioned solutions tackle the same problem but from a different perspective.

Any speaker with a flat response will exhibit the same problem if put in the same the room. If sonic performance is your first priority, then additional room treatment is required. If you need to balance sonic performance with room aesthetics, then something like the PARC would be the solution.

I agree with all about the room being the issue. I had similar problems with my similarly sized room. The problem was solved with judicious use of ASC Tube Traps and a Rives Audio PARC. You may not need the PARC as your issue is at around 80Hz while mine was at 31Hz and 37Hz, frequencies that fall below the effective range of even large traps.

Guys,
thanks for your input. I can see from some of the responses that not all seem to have understood my intitial posting and the reason for this thread. As I said I am very happy with the bass I have in my room at the moment. Because of the Aerial subs and their built in EQ I have very nice and smooth bass now. So I do not fully understand why some of you suggest that I should use a unit like the PARC. Is that because you think I should not use the Aerial SW12 subs and their built-in EQ but have the 20T running full range? I must say I find the bass in the SW12 to be phenomenal and they also integrate very well. Also I have found the midrange to improve when I removed the heavy bass burden from the 20T. I have looked up some other threads about JL subs and Vandersteen subs and found that this is a quite common solution to do what I have done, to split the bass signal between sub and main speakers.

My initial post and the reason for this thread was if there are other speakers that would do the job my Aerial 20T´s now have in a better way. For example I am thinking of line sources that roll off at 100Hz or speakers that excell in the midrange, even better than my 20T´s. And btw, I am definately not going to throw in more bass traps in my room...