Killer used integrated for <$500?

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

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. 

+1 on the PS Audio Sprout 100. 

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!

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.