While technically you could power a pair with an NX1000D, you'd be leaving a lot of performance on the table. The "Marty" subs are generally designed for the Dayton Audio Ulti-max 18" Sub which is a high excursion consumer sub that is generally considered to be a good value for the DIYer but they require a lot of power (and a big cabinet) for maximum effect. The driver isn't particularly efficient (87db) and is a 4Ohm load.
You can power a pair of VBSS subs with an NX1000D because they use a different driver, the Dayton Audio PA460, which is a pro -PA driver that the designer, Matt Grant (mtg90), saw potential in and uses the DSP in the amp and cabinet design to make a viable subwoofer out of it. The PA460 is an efficient (98db), easy to drive (8Ohm) driver and a pair can be powered to max potential with an NX1000D. The extreme value of the VBSS, is not only that it is cheap to build with a $100 driver and single sheet of MDF, but also that you can power a pair off of the Behringer NX1000D or up to eight from a NX3000D - that's some serious firepower for not a lot of amp.
The Dayton 18" Ultimax used in the Marty subs digs deep and is particularly good below 30Hz, it's a little lean on midbass, which is where the Dayton PA460 used in the VBSS shines. Some people use both a Full Marty and a VBSS (tuned higher to 31Hz or 40Hz) in the same system. If you want serious output below 20Hz the PA-460 isn't for you, but it's a beast in the 30Hz and up region where much of the bass we see in movies and music is. Either the Marty or VBSS subs would be awesome in your room, and either should blow the socks off your Klipsch sub.
7.4.4 Theater Room: JVC-RS500, Silver Ticket AT 2.35:1 142”, Onkyo RZ830, Anthem PVA-7, Panasonic UB420, Apple TV 4K, JBL Studio 530’s, Dual Driver VBSS
3.1 Living Room: Samsung 64” F8500 Plasma, Anthem MRX 300, Dynaudio Audience 52’s, Dynaudio Audience 122C, NHT SubOne, Roku Express (2019)