Just saw the A/V forum video review from Peter B. on this speaker. Looks promising. I confess not having read through this thread, but the Impedance spec is no where to be found on their website.
Cube Audio Nenuphar Single Driver Speaker (10 inch) TQWT Enclosure
Cube Audio (Poland) designs single drivers and single driver speakers.
Principals are Grzegorz Rulka and Marek Kostrzyński.
Link to the Cube Audio Nenuphar (with F10 Neo driver) speaker page:
https://www.cubeaudio.eu/cube-audio-nenuphar
Link to 6Moons review by Srajan Ebaen (August 2018):
https://6moons.com/audioreview_articles/cubeaudio2/
* Frequency response may vary and depends on room size and accompanying electronic equipment.
Principals are Grzegorz Rulka and Marek Kostrzyński.
Link to the Cube Audio Nenuphar (with F10 Neo driver) speaker page:
https://www.cubeaudio.eu/cube-audio-nenuphar
Link to 6Moons review by Srajan Ebaen (August 2018):
https://6moons.com/audioreview_articles/cubeaudio2/
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Parameters (from Cube Audio):
Power: 40 W
Efficiency: 92 dB
Frequency response: 30Hz - 18kHz ( 6db)*
Dimensions: 30 x 50 x 105 cm
Weight: 40 Kg
* Frequency response may vary and depends on room size and accompanying electronic equipment.