Ad is for one 511 amp. (ignore the 560 audiogon didn’t have a pull down for the 511 and it was required field) One of the newest modles by Soulution and is frequently used to demo high end gear at electronic shows around the world. I had two, one is sold. One left. This amp was bought as demo earlier in 2017. One owner. Used it to power my Magico M3, and only selling because I bought the 701s. The 511 is 80% performance of the big 701 monos at a small fraction of the cost, the amp is cut from the same cloth as the 7 series. One of the best amps for resolution, soundstage, speed and bass, and not harsh at all on mids and highs. Very good condition, works perfect. All original packaging sn 511-0023. Switched to stereo mode, but could be swapped back to mono if someone is buying a second one. Great price.