I recently bought the 532H (similar to the 533 except only 2 channels) and my conclusions are as:
Build quality- easily 2 steps (0-10) lower than the older 400 series amps. Top plate sheet metal is a thin affair which noticeably resonates if you tap on it. Front face plate looks not as good as the 400. Tolerances are loose as the top plate was not properly aligned with the top edge of the face plate.
Sound: Clearly 1-1.5 steps BETTER than the 432 or 436. Bass is very robust and the 532 has some degree of warmth which makes the listening experience delightful and non-fatiguing. Do note that IMO, the 400 series were also very good sounding, but the 532 is significantly (and I am a statistician) better. Would I commit to picking them out in a blind test vs the 400 series amps? Most likely.
Build quality- easily 2 steps (0-10) lower than the older 400 series amps. Top plate sheet metal is a thin affair which noticeably resonates if you tap on it. Front face plate looks not as good as the 400. Tolerances are loose as the top plate was not properly aligned with the top edge of the face plate.
Sound: Clearly 1-1.5 steps BETTER than the 432 or 436. Bass is very robust and the 532 has some degree of warmth which makes the listening experience delightful and non-fatiguing. Do note that IMO, the 400 series were also very good sounding, but the 532 is significantly (and I am a statistician) better. Would I commit to picking them out in a blind test vs the 400 series amps? Most likely.