klaus has only one other fellow who works with him, i believe, it is a very small shop
he is less responsive on email than over the phone - as a result i have called him a few times and he answers in person, and is very responsive and chatty when we connect in person
klaus’ amps have fairly high input sensitivity (relative to industry stalwarts like pass, ayre, hegel, krell), so any electrical hum or input noise seems magnified
just need to make sure your signal and power feeds are quiet/well filtered
leaving aside the little niggles, if one gets his amps working right, they are a tremendous (no exaggeration) value and excellent performers, irrespective of price
