Standmount speakers with Line Magnetic 518 SET amp?

Harbeth or Tekton Double Impact Monitors

Both play well at low volumes.

I suggest you find speakers you absolutely love,then mate power to it..your going backwards

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