Got it. By the way, which one is better in terms of DAC, regardless of headphone output? I wanna further upgrade by adding an Amp. Thanks.

I just use IEMs like Brainwavz M1, SoundMagic E80, Westone UM1, etc.

I would highly recommend you Sennheiser HD 600's!

The Sennheiser HD 600's are the best classical one I've ever heard at this price (under $500). They sound like the actual live classical concert most!

Try Alessandro MS-1. It's a laid back version of Grado SR80e's which sound warmer. (PS: I personally don't recommend Sony 7506's, cause they are DJ style and might sound harsh and rigid.)

I usually use laptop in dorm and PCs in computer lab. The lab PC's headphone out has plenty of background noise while using IEMs. Hope to find a easy solution for this.

The Audioengine D1 is about twice the price of the Fiio's E10K, does it worth the extra bucks? I'm seeking a under $200 portable dac with headphone jack (USB driven, not rechargable ones like E17K). Can anybody tell me which one is the best bang for the buck? Why? Thanks!

If you wanna budget money I highly recommend the ATH-M50x. The Sony 1A is much expensive here is North America than Japan, China, etc, and will be cheaper in the future.

The latest version (same style packaging with HD 800's/HD 700's) sounds close to HD 600, and not as dark as earlier versions.