Sorry for the late reply. It plays way lower than 40hz. I just tried it with Sinegen. At moderate volume you hear and feel it working at 30hz, and if I put my fingers on the driver I can feel it moving at 25hz, even less. At “party” volume, well… Sinegen goes to 15hz max., and touching it I can basically count the 8 inch driver going 15 times a second in and out. And I’m seasick now, thanks. 
lol
For the “Competently” part? Huh, that’s another question. The problem with subs is, as far as I know, you either get low, “cinematic” bass (like this), or tight, analytical bass with a sealed sub, but not both. Long story short, in theory, it’s the “chuffing” port that gives you the low-but-imprecise hertz, and a sealed sub cannot “chuff”… but also cannot go that low.
If you absolutely want precision (for music production, for example), the least expensive sealed/closed sub I found is the Kanto Sub8 (specs: 125W RMS, min. 35hz), for 250$. And, again, in theory, Sub8 will make you feel like you’re in the studio (…with a big carpeted floor, absorbing the lowest hz before you can hear it?), and the Monoprice one will make you feel like you’re watching a show.
https://www.amazon.com/Kanto-sub8-Powered-Subwoofer-Extension/dp/B01DPRYXSY
Still, be aware Zeos reviewed the sub8 and said the cutoff wasn’t working as it should – I don’t know if they fixed that – yours to decide if it matters. And yes, there’s a Sub6 for cheaper – if you can find it. But the Sub8 can probably be found for less $.