Perfect, almost perfect!
Very good sound, like in a concert hall, but for my taste there has to be more bass. In its price class certainly Best buy!

I bought them today and I am really enjoying them. I compared them to theSony (600, 900) headphones and there was no comparison. I checked out the Sennheisers and they sounded great too, but for the same sound quality I would've had to pay a lot more.

For the price these AKG 501s can't be beat....

Now if I can only decide on what speakers to buy..........

A very open and lifelike sound that misses only in the extreme bass, but that may be typical of circumaural 'phones like these. I compared them to the highly regarded Sennheiser HD600 and preferred the AKG. For one thing, they are more precisely balanced between the left and right sides. I tried several samples of the HD600 and they were all slightly misbalanced, whereas the K501 was dead center with a mono recording. The Sennheiser was slightly more comfortable due to the velvet-like cloth they use. The K501 uses a harder foam covered with a net-like cloth, however, they are self-adjusting which the Sennheiser is not. But all in all, the K501 is clearly better--more open sounding, less closed-in and better balanced. Plus it is less than half the price of the HD600.