I bought this to add to my two Behringer B212D full range powered speakers to add a bit more bass. 5 stars overall because even thought there are caveats about its performance the price point makes this an absolute bargain. We are now using 2 of these with Pyrit 12s and our Behringer PMP6000 for the band, playing halls and outdoor events for up to 200 people. They really are the bargain of the century.
It came well packaged, and despite its solid mass it survived shipment intact. First impressions are very favourable, it seems well constructed and weighty, the amplification panel is recessed to avoid transit damage. It has every feature you could reasonably want - stereo input, stereo link, ground lift, phase inversion, crossover with high pass out, shape control, level and frequency controls - all of which work and make it very controllable within the limits of the unit. It took me some time making adjustments to get it to integrate well with the B212Ds. I found it best to simply use the pass through option to avoid the overall tone becoming thin. I could not get 125db (that would be transient peaks only (rule of thumb knock off 10db when you see speaker specs and you won't be disappointed) with the whole rig going. That said the ensemble still hit 115+db giving a full range properly balanced sound which is definitely loud enough. Secondly, I had to buy some castors - it's just too heavy for me to shift without them.
In conclusion, much better and more versatile than it has any right to be at this price, there are louder subs, but not anywhere near this price point. So buy 2 - we did!
Tip: if you are using a mono input into one channel bridge that to the second channel - noticeably adds to the volume.