Standmount speakers with Line Magnetic 518 SET amp?

Without knowing your budget, the DeVores are a good choice. I think the Orangutan O/96 is a good match for the LM Audio. I also think, if you have a small room the Vandersteen Treo, 3a or even 2ce Sig II would sound great. I have the Sig II but if I had the cash I'd get the Treo or Quattro CT. I have the LM Audio 216ia.

Audition some Proac d2.  Great match with LM.  Best.....

My Merlin TSM monitors have never sounded better than when powered by the LM 518IA

I designed my speakers (Verdant Audio) with a different brand 845 (Art Audio Quartet).  Literally what final voicing was done with.  They are intended to take full advantage of the massive soundstage and extraordinary detail you get from an 845z. 
I would prefer you had a little more power (25-30w) but my Nightshade product is my soundstage and imaging king.  Decent sensitivity at 85dB.  A hair warm with a massive soundstage.  
My Blackthorn will be dead neutral with your amp and will deliver maximum detail.  A nice soundstage but this is about hearing every detail and nuance.   SPL is 84dB.  
In both cases, you want a touch more power if you are going to turn it up to 11 but if you don’t do that, they are just about perfect for an 845.