Was just looking at the Hypex website and noticed they're now selling their own NC400 kit form mono blocks. Rough estimate once posted and slugged with duties and tax I would guess these to be around $2500 landed. I've been using these same amps for over a year now and think they're fantastic value. Drives my Magnepan .7's with ease and some little power hungry Kefs I have too. Would be a perfect match for the LS50 me thinks.
https://www.hypexshop.com/DetailServlet?detailID=7616