The Frank Acoustics Frank AB -2 Tower Sub allows you to put small speakers in it and monitor speakers have grown, keeping everything good about them while giving you the extension you want.

The middle section allows you to slot in your own small monitor speakers. Each tower comes with multiple crossovers for the user to calibrate each section’s response. Monitor speaker not included.
Frequency Subwoofer response describes the range of audible frequencies the speaker can reproduce between 25 Hz (deep bass) and 20 kHz (a piercingly high frequency), which is considered the range of human hearing. In reality, our hearing does not typically extend up to 20 kHz (especially as we get older), and bass frequencies below 35 Hz tend to be felt more than heard. 
The most meaningful ratings include a plus/minus deviation (±3 dB is typical), which indicates how far the sound deviates from a neutral or “flat” response; the lower the number the better, although in practice, speaker placement and room acoustics greatly affect what you hear. Still, the number at the lower end of the range gives you an idea of how low the speaker can play. For example, Monitor speaker rating of 55Hz – 20kHz ±3 dB means you will need to add a separate Frank AB2-Tower subwoofer if you want to reproduce the deepest bass.

Speaker specifications:
  • Dimension : 12″W x 78″H x 18″D .
  • Weight: (6X separate box) Per channel 95Kg
  • Woofer: 9″ X 4  woofer 150Watt Scanspeak.
  • Impedance: 4 Ohm.
  • Ambiance Super tweeter: 1″   3KHz to 25KHz.
  • Sensitivity : 89dB @ 1w @ 1meter @ 1KHz.
  • Monitor speaker not included. 
  • Monitor: (Option  FV-5 monitor) 
  • Crossover: 8 independence crossover.
  • Amplifier : Min 50 watt to Max 300 watt 
Price : from 6.100 to 8.656 USD.