Amp for LS50


I recentl got a pair of LS50’s and will eventually be getting a nice amp and preamp for them.  I’m curious as to what amps pair best with the power hungry Kef LS50’s.  I’m wondering if ClassD audio Sds470c would be a good choice being that its 300watts at 8 and 600 at 4 ohms.  

Im open to all suggestions.  I’d like to keep the budget for the amp at or below $1000 and maybe $500 for a preamp...

Perhaps a used Nova 300?

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Let me be clear, I wasn't necessarily endorsing the Mivera amp above amps by Nord or Apollon that also use the AS1200 module. There are many options out there using ICE and HYPEX modules in amps. Apollon, Nord & Wyred4sound (used) should all be available in your price range. d2girls is correct that the KEFs will reward you with better electronics, no doubt about it. 
Wow, That Kinki Studio exm1 looks to be insane...  I read Nonoises review (in addition to some online info / reviews).  Looks to be quite the integrated amp for $2200.  I’m not sure if I have that in my budget right now though, unfortunately.  We’ll see...

Now all I need is about 10 more good choices to really confuse me, hahaha.  
I had my LS50s running off my Ayre VX-5/20 while I was awaiting my new floorstanders to be shipped.  I was amazed at how well they performed with high quality power.  I have attempted to find a less powerful amp to run them in a second system and realize after some trials they really shine with quality watts.  You may want to acquire the amp upgrade first and enjoy what the LS50s can do while you are awaiting your speaker upgrade.
Good quality amplification (not necessarily big power output) will make your LS50 perform optimally. The LS50 need good quality amplification and upstream electronics, as somebody has already suggested here, in order to hear what these speakers are capable of.

I heard these KEF LS50 paired with the Naim Uniti Nova (streamer/DAC/integrated amp), which is an all-in-one box solution, and they sounded fabulous together very musical very fluid solid punchy and had excellent musical drive or rhtymic drive. The Naim Uniti Nova is rated at only 80 wpc @ 8 ohms and its power amplifier section uses class AB design. 
The Naim Uniti Nova has a very good digital streamer/DAC as well as integrated amp sections. 

However, the Rotel RA-1592 integrated amp and the Musical Fidelity M6Si integrated will also make your LS50 to sing. But as you upgrade your amp and upstream electronics the better they will sound or perform. Unlike other speakers within their price range (sub $2k/pair bookshelf speakers) these KEF LS50 would have to be fed by quality electronics in order to perform and sound good.
If you are seriously considering musical fidelity, check out upscaleaudio.com. He has the m2si integrated at 40% off the 1k msrp. Unless you go used and get more for your $$$. And can stretch it a bit, this Hegel here on AUDIOGON would have plenty of power for your ls50s 

https://www.audiogon.com/listings/lis98g51-hegel-h-160-h160-h-160-integrated-amplifier-solid-state