The XLS does have a fan. If I put my nose to the amp case I can hear it. I seriously cannot hear it from 1 foot away. Love this amp.
Back to Klaus's amps - I have never had one, but have had many recommendations to check one out.
When I finally get back to the point where I have built a room where I can actually turn things up, I also want to look into Klaus's amps. His designs are supposed to be great. As it is now, everything I do is in the family room which is open to a large space. A good sounding amp would never get used.
As for fans, I've had a Crown amp with a fan in the past and absolutely hated it. First, I put in a supposedly much quieter fan, and that worked for a month or so. After that, the fan made such a racket that I threw the amp in the trash. I hate fan noise so much that I'm typing this on a fanless computer. It has a bunch of copper tubes running from the CPU to the case. I bought a different computer as my home theater computer. It had a single fan on the CPU, and that was it. A year later, I can hear it from 15 feet away. Unfortunately, fanless computer cases cost more than an entire computer, so I can't afford to have a HT computer with them. Anyway, I refuse to buy an amp with a fan, unless I can put the amp outside the room.