Yeah I wouldn't go by DT low end specs, notoriously "optimistic", so without a third party test I'd just discount it a lot, probably consider it an f10 at best. Goes for their "subs" as well as speakers. I was just sitting outside on my deck and liking how my Dayton IO650s have worked out the last what 6 years now out there? Still enjoy them a lot, and if I want to bring up the low end I have a sub on a wireless transmitter I can add out there when the weather is good enough