Conclusion: I have this sub in a sealed .40 cu in box powered by a Kenwood KAS5001PS Mono amp pushing 300W RMS. I have it crossed over at 80Hz with Polk DB651's in the doors with Polk DB461's behind the seats and Polk DB1001 Tweeters all powered to max RMS power, the sound quality is incredible.
Conclusion: I purchased these for some DJ speakers for the mid bass. These sound great and heave very clear sound. I have then wire in series for a 8 ohm load and am pushing 350 watts RMS and these handle it like a champ.
Conclusion: 6 months and counting. I love the fact that my db840's are marine certified because I have them in my Goldwing motorcycle and they have performed flawlessly. Can't wait to push these babies with the marine amp that I purchase.d from Sonic.