I've owned the Mani-2s for about 15 years. I now use them in my workshop but they were in my main system for a while. The bass from such small enclosures is quite impressive But to achieve this low frequency performance, they are not very sensitive and need some good amplification. I was driving them with a Krell FPB-300 which worked very well.
I don't have any experience with the Devialets.