Budget/value SS power amp recommendation

also,I don't think the Schiit Audio Vidar is Class D??

Emotiva XPA100 monoblocks
Outlaw Audio M2200 monoblocks
as well as other offerings in their lines

+++ for the ADCOMs
Still running a GFA-5500 as my back up. It never lets me down and (with a long warm up) it always sounds good.
Also a big + for the B&K....Jim

I not long ago replaced a Musical Concepts-modded Hafler DH-220 (still in use in the bedroom) with a mint B&K EX-442 Sonata I picked up for $325.  200 wpc into 8 ohm, 350 into 4 ohms.  Through a Parasound P5 preamp, my Maggie MMGs sing like canaries.Built like the proverbial tank, heavy, lots of headroom, warm sounding.FWIW.

A brand new Emotiva A-300 can be had for $399.  150 watts rms into 8 ohms per channel.  3 year warranty.  An A-150:  $299.

By the time you purchase the vintage M-4, replace the caps and relays, upgrade the connectors, clean the pots etc. you would be able to buy several of those Emotiva amps, even if you do the work yourself!

On the other hand, the M-4 is vintage cool!  Looks do matter!

Thanks everyone for the suggestions....for some reason. A Yamaha m series seems to be calling my name, based partly on suggestions here and not the slim chance of a used belles.....

looming at an M-4 for stability and ease of repair if needed....there is one locally....may try and snag it over the weekend....

Cosmetics irrelevant? Crown XLS 1002 at $299.  Those pro amps do well with low efficiency speakers.  I would not use them for high efficiency speakers (hiss).  The fans are variable and virtually silent. The fans probably will not even switch on with the load you will be presenting to them.  Try one and return it if you don't like it!

NuPrime STA-9 Class D. 120 watts/ch. Beautiful open sound. Can drive just about any load a speaker can. RCA and XLR inputs. $649
I owned one, and it beat out many amps costing much more. Can be bridged for more power. Only way I could get better sound was with a vintage Krell running Class A.

NAD, Parasound, Emotiva and Adcom all make good budget amps.  The Emotiva and Parasound are naturally a bit bright so choose your DAC's wisely.  The Tube Preamp will help with this as well.  The Adcom range is a bit more neutral in tone and has a big soundstage.   I have no personal experience with NAD.  
When picking a solid state amp try to find the one that weighs the most so you know it has the balls to back up the spec sheet.  

A couple of Outlaw M-200 monoblocks would do nicely, and should cost about $400 on the used market.  Plenty of power, transparent, and neutral.

The later Adcom amps (5300, 5400, etc) are also very good and can be purchase for perhaps half of that.

Rega power amps are low-cost, sound like music to me and often pair well with tube preamps.

Ping me.  I am just getting ready to list an amp that fits your needs perfectly.  Teeshot

Kinergetics Research has a few amps under $500.  They are out of business and a good value sound per dollar. 
I bought an old Marshall Leach Heathkit amp for $250.  I am rebuilding it now,  but it is surprisingly nice sounding.  
Sumo has the Polaris, they run about $300
Rotel, Parasound or Adcom from the early 80's can all be had easily under $500...Adcom 535 is around $200.  
I'm sure a couple of Chinese amps are decent,  Here is a quad knock off by Douk audio:  https://www.ebay.com/itm/Nobsound-Classic-Power-Amplifier-Audiophile-Hi-Fi-Dual-Channel-Stereo-Amp-1...

I saw a PS Audio Sprout on eBay for $ 499.   That would be a great addition to your listening needs.

Shad 

Thanks everyone for the suggestions. A used older AVA piece would definitely work 

re why not a tube amp.  I have only used this las35a 15ohm version with tubes for over 15 years.  On a whim I hooked them up to a beast of a Bryson amp and was floored.  The power and clarity really owned these old things.  Donnie I’d like to try solid state.   

I was in a similar situation. I found an AVA Omega Star 250EX (rebuilt Hafler chassis made from 2004 to 2007) on for $225 shipped. I must say I'm very happy with it. Power for days ( (under) rated 150 watts per@8 Ohms). Drove my 4 Ohms Cerwin Vega VS-150's so hard they were pounding like subwoofers, and scared me. Never heard it clip before actually. It's too powerful for me. Which is awesome! Sounds amazing with a tube preamp (modified Bottlehead Quickie). Bests my rebuilt HH Scott Stereomaster 200 for sound quality with a Scott Nixon Tube DAC. Bought it for a 2nd system. Mainly for rock. And to try the tube Pre/SS amp thing. It's become my main system. Haven't barely touched the Scott since I got the combo working good. My only concern is that, since there's not much info about it. I don't know what to compare it to, if I go to upgrade. I'm afraid that, unless I spend a lot, I won't be happy with the new one I buy. Because of this. I'm thinking Class D next. Maybe an Ice Power, or Hypex amp. Or Class D Audio. I like warm sound though. The AVA isn't incredibly warm, but it's warm. 

With your requirements. I would be thinking Yamaha myself. I've seen people say that the only reason they're so cheap. Is because they sold so many of them. And that if they didn't. They would be selling for much more. Very overbuilt. Known for lasting forever. Supposed to have amazing sound quality. The specs are certainly amazing. That's for sure. And most have plenty of power. I've seen very nice ones sell in your price range. There's a lot, and I mean a lot of guys that swear by the Yamaha Natural Sound. I keep thinking I should try one myself actually. But AFAIK. They're more on the neutral side. I think they're a great value though. Either way. 

Good luck. 
Andy B. 

kbuzz, with 15 ohm speakers I might rethink your request for a solid state amp.  I'm making some generalizations here, but this could be a speaker that would work better with a tube amp.  I didn't look up the impedance profile of the speakers you're using, but just seeing the 15 ohm spec makes me think that you could be much happier with the tubes.

Michael

Check out the Emotiva site; they have many acceptable amps in this price range.

Older generations NAD is a reliable contender. I cannot guarantee for newer ones, though.

sufentanil,

What made you pick that name? It is quite unexpected.

I like the Forte 1a amp. It's 50 amps per channel, all at class A. It's in your price range (used) & is a great amp. Note that I've never run it with 15 ohm speakers though.  

Thanks all for the great suggestions. Will be used with some vintage 15ohm LS35as. Since it’s going to be used with some vintage euphorically characterized pre amps I’d like it to be on the neutral l size of things...but would not turn down a monarchy amp...that’s a great one

What are your speakers for this 3rd system ? I am a huge fan of the Nuforce STA 200 amplifier, $499. from Audio Advisor ( still ). It has a lot of gain, so I do recommend it cautiously as it might amplify noise further up in the chain. Enjoy ! MrD. 

You list some nice choices.

Parasound, NAD, and Rotel are also pretty solid options in that price range.

Other options include Marsh, and old Onkyo or Yamaha, Conrad Johnson's Sonographe series, Outlaw Audio, Monarchy, or maybe an old Forte.

What speakers are you mating it with, and what are your sonic preferences?  That might help to narrow down the list a little.  Nonetheless, a $500 budget is perfectly adequate to get something decent on the used market.

Michael

Schiit Vidar used.  Class D Audio.  

NAD is good value and sound.