For sale Audio Pro Rev. 4/5 Modified passive version. New. 2 way passive monitor speaker (pair). Audio Pro modified. Rev 4 Design. Custom cabinet damping. Model 2031A are amplified speakers. I suggested 2031 passive design, and to use any good 40-100 Watt amplifier. Check out the Behringer website for a picture. A modified set is $448. We modify the 2031 to be a near field monitor where midrange tone is "warmer" or slightly receded image by a 3db through about at octave between 800 - 2000 H3. A far field monitor version is slightly brighter or stronger midrange and designed to listen at 4 to 8 feet distance. Basically flat response is perceived at that range. Near field version is for 2 to 5 feet away listening, and indeed most BSEE acousticians agree that a near field should be dipped in midrange. In both cases, the modification consists of improved multi section crossover (it presently has a very simple 4-part crossover) as well. We install a dampening blanket between the internal chambers, dampen tune one of the port slots and finally apply soft felt clone dampeners to improve midrange level and tonal match to crossover. The cabinet is now tuned to reproduce 40 Hz powerful and clean. The speakers are very heavy design with cast frame woofer, using high density MDF cabinet, very well done. No grill cloth is included by design. Shipping can be $38 or so to get them to you.