the difference between HD650 and 600 are minimal compared to other models, you can't go wrong with either model. Technically HD650 is slightly more refined and have better driver matching. (from objective data, not from personal impression)

  Have you find any international electronic store?  250ohm is not that bad, but as referring to the measurement, I would choose 600ohm version even its slightly more expensive.   BeyerdynamicDT880250ohm   BeyerdynamicDT880600ohm   You can see the 250ohm one is brighter and bass's...

  Smoothness means no harsh over exaggerated treble and well controlled resonance on the treble spectrum. Too much treble resonance or exaggerated treble energy will add up causing listening fatigue. Clarity means well controlled resonance results in better resolved image and thus you can...

  HD600 and HD650 are very similar in most ways, HD650 are just slightly more refined and slightly darker sounding than HD600. Many will consider them as musical which means you can enjoy the music without being distracted by the highs(no harshness). They are as detailed as DT880 and Q701 IMO...

Right now I have tried both, they are both bright headphones, so you will expect light bass because of their brightness(both are not any means bass light). But, Beyer DT880 have more bass base on my personal impression. Both have very clean sound. Q701 has wider sound stage I will say, but some...

  It is a common myth many will debate about.   If you believe in burn in, then do whatever you think you need to burn in the headphone, because listening is a subjective experience so your phycological sense play a part in this process.   IMO, a pair of headphones' sound should not change...

  Indeed， but most average recording will sound better on great headphones IMO. BTW, what will you define a recording as bad?

This is just personal experience: By dark I mean less treble. To me, it lets bass and mid stands out more and you can find more detail on bass and mid instead of disturbed by a lot of treble. Especially with bright headphones, I find it give a false sense of detail, I cannot focus on the music...

Most people will comment that K701 is a little bit bass shy, I will suggest go with Q701 which has slightly more bass. DT 880 is also a good choice as Q701 and DT880 are quite neutral and will generally fit many music style.   BTW, what kind of music you listen to the most?   My personal...

  I cannot tell you the difference without data or without actually trying them.     OK, my point is, as long as you have sufficient volume (like 70% volume make your headphone sound very loud), you don't quite need an amp. An amp is only needed when headphone is under driven ( not enough...

Depends on what sound card you have on board. Computer is a very noisy environment, out board DACs will sound cleaner. If you cannot decide, try direct drive from your stock sound card first and compare this to your HD598. If it sound worse than your HD598 or your volume nob turn to full with...

From a not so experienced ear.   With 2 hours of listening and compare to HD800s, I felt like K812s go with different presentation of music (laid back? kind of. Maybe not try to grab your attention a lot). If I were to describe HD800s' presentation, it is more pin point accurate and smaller...

HD600 HiFiMan-500 DT880 are easier to drive, so any $100-300 amp will be good to start   O2 from JDS labs, Ifi ican from Ifi Audio   AMP/DAC combo will also be good: Meridian Explorer, Audio Quest Dragonfly   HD800 is  more amp picky   Quote:   I wouldn't say it must be a huge...

With passive speakers, yes.