Killer used integrated for

Not to talk down any of the other suggestions, but NAD is your best bet as far as availability, performance and price.

Thanks, time for some break in. Search for some ProAc D-2's or Tablette 10 continues. 

Congrats on your purchase!

All amps can use a “break in”. Good choice on the Marantz, it’s a nice unit!

mcondo, I'll add one thing. My son bought that same integrated. The way he talked, it was pretty sterile sounding out of the box. Sound improved the longer it was run. Take care

Hope you enjoy the marantz; they really play well and they have gobs of power.

Look on ebay and craigs for older Peachtree and Rotel.   Like this
https://www.ebay.com/itm/Peachtree-Audio-iDecco-Integrated-Amplifier-w-iPod-dock-Black-Used/27455114...

OP here, went with the open box Marantz pm6006. Price was great, easy breezy purchase from Music Direct. Received in 1 day. We'll see how it performs in my second system which uses my vintage ADS L710's (for now) and Sony BluRay/CD/Sacd player.. Thanks to all who shared their opinions. 

A used Yamaha A-S501 or 701 could be found used. I have the A-S701 and believe it to be great at it's price point ($750 new).

only one person mentioned Rotel. so, here is another vote for it. I prefer it over all other amps I had (Nad, Marantz). 

+1 another vote for the Marantz PM Intergrated line. I sold my brother my older PM 8005 when I moved up to the Krell K300i and he loves it with his Klipsch speakers and SVS subwoofer. 

I have a Mcintosh MA7900 that is another one to look at but they're not cheap.  

+2 on the PS Audio Sprout 100.

@builder3 thats tough to beat at that price point. Classic Marantz sound.

I agree that the Marantz is a good deal at that price. 

@builder3 thats tough to beat at that price point. Classic Marantz sound.

hshifi, I've been to Holm - thanks for the reminder. My son has a Rega Brio 2000 that he is happy with, I'll take look at their lines.

Hello,
I agree with the Rega Brio. If you feel you would be upgrading the Rega soon I second upgrading the amps on your existing system. You can add a nice Rouge RP1 tube preamp for $1500 later to improve on the system and Rouge has home theater pass through so you can integrate it with your surround system. Last  I would be checking out used gear at stores. Most will ship. They take stuff on trade-ins all the time but only list on their own website. The Brio, Rouge, and nice used equipment is all sold at my local store if you don’t have one nearby. https://holmaudio.com/shop/

Yamaha amps are undersung power horses in amplification. 

Krell kav 300. It’s slightly more than $500 but definitely has a typical sound signature of Krell. It looks good too. 

Another for Rega.Brio is great, or if you want to save a little more and are ok with larger size, the Rega Mira 3 line was really great (what I am currently running).  Not super powerful, but with Bookshelf monitor style, the integrated does great, can run a sub, run as a pre or just amp, remote control, and matches great with their CD player or DAC~r. 

I would look for an old tandberg integrated may pay a little more than 500 dollars but not much.

Yamaha A-S500. Measures better than some amps costing 5X its retail price and sounds great.

👍👍👍 on Exposure. Just plain musical and fun!

I also recommend the Exposure.  Helped a friend find a decent used integrated a couple of weeks ago and found a used Exposure at a local dealer for $500.  Excellent value; no bells or whistles, just quality amplification with analog line inputs.  

@mcondo - get a lovely vintage reciever... recently picked up a Luxman R-1050 and its extraordinary! Rosewood cabinet, lovely glowing meters so the vibe is right but, it PLAYS BRILLIANTLY! Can pick something like this up for $5-$600 so right in your wheelhouse. 50x2 of clean bountiful power that's enough for any relatively efficient speaker. Plenty of options but that'd be my route. GL!

+1 on the Exposure. I had one here for a while. It definitely plays well above its price. Iirc, they also sell a matching amp in case you’re looking for more power down the road

Rotel RA-980BX. I own one since 1992 and except for some capacitors that needed to be changed 10 years ago, it has performed flawlessly. Clean and simple design, quality built, plenty of power. They do not come up very often in the US but if they do they usually go for less than $500. Here is some info on it: https://www.hifiengine.com/manual_library/rotel/ra-980bx.shtml

I have an excellent condition Audio Refinement Complete in my closet. IMO a step above Rega Brio R and Rega Mira 3 I have owned. I don’t have a use for it, but keep it because it’s so good.

I currently use Vista Audio spark on my desk. Great little amp but only 20 watts.

Someone mentioned the Parasound Zamp. Also owned. Very clean and analytical sounding. It almost sounded like Class D. I didn’t care for it but I imagine it would be real nice with a tube front end.

Someone also mentioned the little Emotiva 50 watt amp (also owned). It’s good for money but a step below the Rega amps I mentioned.

Good luck!

Used better or dual mono Japanese integrated for $100-150, in OK but flaky shape.

Taken to a pro tech who is audiophile oriented and rebuilt to beyond original spec for $350-400.

total, $500, and not going to be equalled for at least a few thousand, if purchased new.

maybe not easily beat -at all.....depends on the amp found and at the core of the rebuild.

but one has to put the work in. No (risking of) pain, no gain.

Also, Sun Tzu: If you sit by the river long enough, the body of your enemy ~will~ float by.

I’m saying that you’ll have to be patient and work for it... wait for it...and chose the right item.

I have heard the Rega Io with the Proac D2's and Tablette's. They sound great together. The best I have heard with the Io was the Vandersteen Wood VLR CT's. Not exactly what you would expect pairing a $3,000 speaker with a $599 amp but they sound great together. The standard VLR @$1650 is a good match as well.

If you are anywhere near Verona NJ you can go listen to the Rega Io with the Vandersteen's, Proac's and B&W speakers at the Audio Connection. JohnnyR will take good care of you. Good Luck!

+1 on the PS Audio Sprout 100. 

The Outlaw Audio RR2160 mk2 sells for $999 new. I saw a mk1 listed for right at $500 recently.  Its well recieved for its price point. 

the M2si is rated at 75w/ch into 8 ohms, 135 into 4 ohms...

OP here. Wow, great suggestions. To clarify a couple issues: using the word "killer" was only meant to identify amps that perform well above their price point. I know performance will not be the same as the big rig upstairs. Second, speakers will be ProAc monitors, not quite sure which model but along the lines of the D2 or Tablette 10. 
Looks like i need to do a lot of research/shopping.

You might get close with a Zpre3 Pre and a Zpre V3. 2 channel power amp for close to the 500.00 mark.. If that is an option. Nice package, great options.. Vary compact too. As small as most integrated packages.

Regards

Just keep what you have, swap the amps to 2 channel and be good. Not going to find much better for the $ you are talking about. And you get Audyssey to deal with room funkiness.

I found an older Audiolab 8000A for $300 a few years back and it's great. 

For that price used, try it and move it on if you don't fall in love.

https://www.usaudiomart.com/details/649634586-vincent-audio-sv129/ $385 used, down from $1k. 

I've been looking for something similar. Mine is specifically for a pair of EPOS M5 speakers which are 88db, 4 ohm bookshelf speakers. (Recommendations welcome.)

A few things that have been on my radar are the PS Audio Sprout, the NAD 3020, the Emotiva TA-100, and the Nuprime iDA6 which is on clearance for $350. You can probably get to some things a bit higher than this list if you are looking used, but of course that's dependent on what you actually find available used. 

'Killer' is a matter of perspective!For a good value in new, how about the Yamaha integrated amps in the price range?

Ps audio sprout 100. 

+1 on Rega Brio. I just sold one on another marketplace. 

Also, killer is not the word I would use for any of these.

Good luck

Not sure how many watts you need, but Vista Audio's Spark is great.

Bought an Hegel H100 for 650usd. It’s a bit pricier but nothing compare at such price.
You will get depth, great timings and imaging, soundstage, bass, beautiful midrange and Hegel liquid sound signature at 120w@8ohm and 240w@4ohm. Plus a usable DAC. Good luck if you want more.

10x the Musical Fidelity m2si.  I loved this amp and should have never sold it.  40wpc is BS.. I don't care what it's rated, it played with the big boys.