How low can you go? With Definitive Technology's DN8 [€499] and DN12 [€999] subs, probably low enough. These are front-firing 8" and 12" cubes with dual sidefiring passive radiators and 200/500w of class H power, "intelligent phase" which auto-adapts to the chosen low-pass filter and 'loud', 'deep' and 'flat' EQ presets. Those adjustments and the sub's level can be set from the seat via the included remote control.