The DT770's and DT990's are the best headphones I've ever tried, and I have just about worn out a pair of each over the last few years. Excellent sound, and very comfortable. Get one of each--the open 990's for neutral monitoring, and the closed 770's for bigger bass tone in your ears while jamming along.
The difference in price is because there
are two different models, and I believe one of them has been discontinued. It's the one with the 600 ohm impedance that has been disco'ed if I'm not mistaken. They're perfectly good phones, you just have to have a desk with the right impedance headphone output, or with plenty of gain on the headphone amp. They will be problematic with low-output headphone amps. I have no idea about the Apogee.
They're worth
more than $150 IMO.
