Standmount speakers with Line Magnetic 518 SET amp?

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.  

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

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

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.

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

Harbeth or Tekton Double Impact Monitors

Both play well at low volumes.

Falcon 3/5

Devore gibbon 3xl..how do theybdifferbfrom mm d3 capo

Not sure your price point, but check out the DeVore Gibbon 3xl's -- Fantastic match with the LM518.

(I'm a LM and DeVore dealer)

Call me a B&W fanboy, but I've always loved the 805 series.  They are nice looking, sound great, and have a surprising amount of bass.  Great imaging as well!  Plus, they've been around a long time, so you can get a nice used set for the lower budget, or the new diamond series if you can afford it.

Thanks very much!

The de Capos are really good, though I like sealed box better and the little Harbeths are now particularly good.......they weren't before.  They deal very well with room acoustics because of the sealed box, you don't play loudly so that is not an issue, they don't move a ton of air so you don't need a heavily massed stand and they are involving.

Take a look at Reference 3A de Capos, 92db sens, detailed, good bass for a standmount, 8 1/4 in woofer, no crossover,  good at low volumes

i use mine in a 20x12 ft room with 4 watt decware mini torii, plenty of power unless I have a rave