I have owned the Def Tech BP30 and it was good in bass and relatively easy to drive, but in my experience Def Tech speakers are limited in positioning due to the bipolar feature and sound a little dark and muddy to some. I sold the BP30 for about $900 some years ago, but still have a pair of the BP10 in another system and remain a fan of Def Tech speakers.
I purchased a pair of Von Schweikert VR2 speakers which have deep bass (substantial output below 30 Hz) and and sometimes can be found used for about $1000. The VR2 have an ambience tweeter in the rear but volume can be adjusted so placement is more flexible. In my opinion, the VR2 bass response is fast compared to Def Tech and can be adjusted by loading the port.
I purchased a pair of Von Schweikert VR2 speakers which have deep bass (substantial output below 30 Hz) and and sometimes can be found used for about $1000. The VR2 have an ambience tweeter in the rear but volume can be adjusted so placement is more flexible. In my opinion, the VR2 bass response is fast compared to Def Tech and can be adjusted by loading the port.