A month and 6 days later, I get these in India. Thankfully zero customs duty. Driving them off the GO 720. Early impressions are very good. To my hearing these sound like a slightly darker version of the HD 600. Need to get some balanced cable for this. Is this possible?
I find them very different from the HD600.
How loud? (I have no idea what 82% or 100% is in audacity or 3 O'clock on O2 without knowing output voltage of source). How do you know it's 20mW? Can you measure with a DMM with a steady state 30Hz on the headphones? Most importantly, are you testing or actually listening to music when the flub-flub happens? The K7XX driver isn't that big. 30Hz test tones tend to do a lot of screwy things to headphones with small drivers, e.g. Grado.Your AT has a huge advantage in that the driver is sealed. Open-back headphones need to work harder (more excursion) to maintain same bass level.Ppl says K series needs amp because they sound kind of dead from an iPhone and also because they are less efficient compared to Grado, AT, Denon, Fostex (dynamic) 'phones.If the K7XX performs fine while listening to music, I wouldn't worry about it.
The person with the uDAC-2 said it was measuring 1.1V with a 60 ohm load at the volume that caused the flapping sound. The problem goes away when the frequency is a little above 50hz.
