European version for sure.
I also own a European N10 with the same US warranty printed on the back of the Instructions Book.
I think Sony uses the same books to both US & European units.
But since the warranty in the US is slightly different from the one used in the rest of the world, Sony print US warranty as a complement of the general warranty I guess…
PS: Yes my N10 also have low volume power, nevertheless it's more than sufficient to my needs.