For the price, this is a fantastic sub, but the inbuilt (DSP?) crossover is not; it sounds very "digital"; compressed and metallic. I guess it would be fine for PA, but not for music. Also the included instruction manual is pretty-much useless.
HOWEVER I use this sub to add some serious bass to a pair of active studio monitors (Yamaha). They have their own crossover, so the Sub 10's crossover isn't needed. It transpires that the input sockets to the sub (XLR and TRS) are actually just connected together, so you can feed the audio into one, and use the other to loop out to feed the active monitors, thereby bypassing the internal electronics completely - the auto-sensing switch-on still works fine when used like this.
This sub is then really outstanding, with exceptional downwards extension, very clean, with a lot of undistorted weight.
The reflex port is front-facing, so the sub can be positioned close to a wall or corner.
There is some audible ringing from the perforated metal grille covering the drive unit when the unit is pushed hard - but the grille is easily removed, and you have to listen very hard to hear the problem, anyway.
So, if you bypass the internal crossover, and remove the metal grille (both really easy to do) then this sub performs as well as units costing five times more. Strongly recommended!