I believe it is the nature of the VA's to peak around 100hz, most speakers do in order to get a higher low fq -3db number. have you tried plugging the top port? then the bottom, then both? another solution is digital room correction.
Speaker With Least Room Interaction
What speaker has the least problem with the type of room up have in regard to bass boom. In other words the least bit of room interaction. Rear bass port, front bass port, bottom bass port, sealed.