I own two MP418SP, and the amp is basically a Crown CE2000 with a novel crossover that makes it a very versatile unit, if not heavy as you well know. The box is rather small, and the tuning is set too high to get down as low as you'd like. Most Pro Live portable subs are tuned at 40Hz, or higher, in order to maximize the benefits of port output to match the program material. Kick drum is typically 50-80Hz depending on drum size and tuning, and the lowest note on a 4-string mass guitar is 41Hz. The only instruments that can produce frequencies below 40Hz are 5 or 6 string electric bass (31Hz), a big keyboard synthesizer, or organ pedal tones. Better to have more punch and less cone excursion from 40Hz up than lower LF extension in live sound applications. I don't think it has a high-pass (subsonic) filter, but I may be wrong about that. A little online research, or measure amp output for LF output roll-off using a frequency generator or test tone CD and a volt meter. You probably could bypass it, or modify it to roll-off lower. If so, you could add fiberglass to the cabinet to increase virtual box volume, and lower the port tuning by doing so. Be careful to secure the fiberglass to provide 3-4 inches breathing room behind the woofer pole vents and the port opening inside the cabinet.