The Sanders Magtech is what I use on my LRS+ and it is the best Class AB amp I I have owned. However, I will use the caveat that it is the best Class AB on the LRS+. On my other speaker, the Yamaha NS5000, the Sanders is not that special. I spoke with Roger Sanders on this amp, and he said it was initially designed for Magnepans (Mag + Tech). I bought it used from Roger for $4k with 1 year warranty.
Another amp that is a bit better on the LRS+, more bass and sweetness, is the CODA #16. I use the Magtech on the LRS+ because it is almost as good as the CODA.