I have had a similar problem with my DMS Isobarik's.
An old time former Linn dealer Suggested that you DO NOT pull the bass drivers (Kef b 139's)
the Brik's are made to be close to the back wall (not out in the room) and on stands that are about 10" high.
Check and try different speaker cable if you can ,
and they are amp sensitive my sound better on my 50WPC tube amp than on my 300+WPC solid state amps,or my several 200WPC SS amps. better bass too!!
The dealer also said that there is a reason that the Naim 250 is the amp of choice for these.
I use a Behringer DEQ 2496 pro audio digital equalizer (analog equalizers still suck) to bring the bass up and EQ the room issues. Google it, there are nice reviews on 6moom and it isn't megabuck audiophile priced (about $300 new) and has a decent DAC too! The tube amp ( custom made by Soft Science is 2X 6L6 per channel) plus the DEQ gave me what I wanted. but my next stop would be the crossover re capping, if i can get to it with destroying the speaker.
With the tube amp I an finally getting real live involving MUSIC from these, were you just let the CD's and records play and you CAN NOT check you email or surf the net because the music has got you.
The Dealer (Creston at Austin HiFi) I call on for another matter (Tocaro speakers) and I happen to mentioned my DMS and the bass issues. He love the Brik's and was listening to his $35,000 Tocaro speakers when I called.
My Next trial will be putting my vintage 1963 Fisher 500C tube receiver (reviewed in Sterophile in 2009)and hear what happens
Let me know what you find
Enjoy da music