I just left mine playing a pink noise file for about five hours to help burn in my uDac-2 and Sennheiser 558's. On a scale of 1 to 10, one being no warmth at all and ten being hot-to-the-touch, I would say it's about a two. I know I spent a few hours listening to a couple albums yesterday. I...

i went to burninwave.com. there are a bunch of mp3s youcan download, ranging from pink and white noise, high and low frequency sweeps, etc. all free. check it out.

Quote: I can only speak to the first part of your post, but the "mod" you speak of is REMARKABLY easy. There's even a "how to" video on YouTube that shows you exactly what to do if you're unsure.

Quote: In the same boat as you. I recently received a pair of HD 558's, and while they do sound good, they sound FANTASTIC with the uDAC2. I bought the HP version since I only plan on pairing it with my laptop. But to think that these two will only improve upon a great sound with...

iBuds. otherwise, i would never spend money on cheap phones.