Never heard of this device and there is very little info on it, in English anyway, on t'interweb.
The one English site I found does quote an impedance of 4ohms for some reason.No idea why as the sub is active so the impedance of the actual drive unit inside the box is irrelevant (to anyone other than the manufacturers anyway

).
Not sure I would be pairing a decent make like Arcam with a very much low end speaker like this. I would be looking at something better from the likes of Tannoy. Yamaha and similar well known brands. OK they are likely to be more expensive but will be a much better match for the Arcam.
And of course you have to factor in matching the sub to the other speakers in the set-up. Though I'm sort of wondering why you don't have a sub already? Normally when you buy a set of surround speakers you get a sub as part of the package. So what other speakers have you got?