Having tried various Tripath and Hypex modules in the past, it's interesting how much better the Neurochromes sound to me. Despite their excellent measured specs, I never really got on with them- something about their sound just didn't sit quite right with me. No such issues with the 686 though (or the 86 I had previously). I know it's a bit of a cliche, but they really are as close to a straight wire with gain as I've come across, and they let you know exactly what the rest of the system is doing- changes elsewhere are immediately apparent.
The only other amps I've heard that were equally as good on kit I'm familiar with (compared them to the 86 I had at an Owston) is Nick's P6100M monoblocks. Couldn't tell any difference between them.
“Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”
Hunter S Thompson