Just got them back and wow, what great service.
The Koss Pro/4AA are bad sounding either.
Bass is deep and tight. Warm sounding,good detail but not exaggerated. Does not sound like the flimsy Sennheiser 5XX models.
Never tried the Sennheiser HD280 Pro, maybe someone can compare them.
Its also overly built, with new cushions I can just tolerate the pressure for one CD session.