Go for Bose Quite Comfort 15 ,which doesn't sound as good as ue6000, or QC20(In ear monitors):sound quality is as good as the best $100-150 iem. You have to spend at least $300 to get what you are looking for. BTW I'm a ue6000 owner, and I pretty enjoy to use them in passive mode with my E07K...

You may consider the ue6000 too, I'm using it and it is quite impressive for a beginner audiophile. And you may do some research whether you need a dac/amp.

Is there anyone can provide me some information?

Oh yeah, I find out when I'm using the amp in passive mode, it improves the quality of the sound, while it does not have big differences when the ANC is on. Thanks a lot!

I'm using a e07k now in passive mode. It is a really beginner level portable amp/dac. It works great for me. According to the impedance stuff I read in here http://www.innerfidelity.com/content/ultimate-headphone-guide-articles-what-headphone-amplifier-and-why-do-i-need-one , it works perfectly...

Do you think it can drive my ue6000?

Is it suitable for my ue6000? It has a 50 ohm impedance in passive mode, and 1k ohm in noise canceling mode.

Thanks! I've asked my friend to borrow me his E07K and I find out it doesn't just increase the volume, it actually improve the sound quality too. I am curious is the E07K enough to push my headphone, and also will a socket powered dac too excessive for my ue?

UE 6000 has big sound units. Unlike a in-ear headphone, it has to use a longer time to burn in. There is no short cut man, so go ahead and keep using it. You will find out that it worth for investment after it is burnt in.

Please, can anyone help me? I need a amp which just meet my requirement without providing exceed function that I don't really use.

I've recently purchased a ue6000 from amazon with a really great deal.(http://www.amazon.com/Logitech-982-000079-UE-6000-Headphones/dp/B0094S36RI/ref=sr_1_1?s=electronics&ie=UTF8&qid=1391301257&sr=1-1&keywords=ue+6000) I am currently using a iPod shuffle to play music, and do I have to upgrade...