PerformanceThe performance of the KNS 6400 was judged after they received 100 hours of burn-in on our test rig. For this test we gathered the usual sources and begun our testing. The setups were as follows: Head-Direct HiFiMAN HM-801, Fostex HP-P1, ASUS Xonar Essence One and STX with modified op-amps.
MusicThe KNS 6400 headphones are full size circum aural headphones. Like its bigger brother the KNS 8400s the 6400s are closed back headphones which means that they provide a decent amount of noise attenuation compared to a set of open back or supra-aural headphones like the Sennheiser PX 200-IIs which we reviewed a while back. Coming from the KNS 8400, the KNS 6400 is not a major step down, however, there are a lot of small details that clearly allow you to spot the difference between the two in the long run. For one the memory foam type pads used on the KNS 8400 are swapped out for a set of more budget cell foam pads which gives them noticeably less noise attenuation. The pad difference also accounts for some of the audible difference in terms of bass performance, the seal is simply not as good with the KNS 6400s as it is with the KNS 8400. Also the way the pads are produced makes them fit less snug than the higher end model from KRK Systems.
Sensitivity wise the two headphones are very similar. Bass rendition and control is not quite on the same level as that of the 8400, but it is remarkably close considering that they are only two-thirds of the price of the 8400. Compared to the BeyerDynamic MMX-300s the KNS 6400s are seemingly less colored, but seem to be equally detailed. The upper midrange is a bit harsher than both the 8400s and the MMX-300s. The Sennheiser PX-200 IIs come within reach of the KNS 6400s midrange wise, but the bass performance of the KRK Systems KNS 6400s is definitely better, and noise attenuation with the KNS 6400s is much higher.
For use on the move these $100 headphones provide good enough noise attenuation in order to be useful. The sound quality is definitely good enough to keep one satisfied for a commute by bus or train, even though you constantly miss the slightly better noise dampening characteristics of its bigger brother. The KNS 6400s might be $50 cheaper but the build quality is the same as that of the KRK Systems KNS 8400s, which is incredible. The only thing you could possibly want from them is perhaps a slightly less studio monitor look, but that is a preference thing. Personally I think the KRK Systems headphones look better than the over-blinged-out rapper endorsed sub-par headphones of today.
The KNS 6400s is a bit lighter than its bigger brother, but it is not something you notice when it is on your head. The only thing comfort wise that is a bit annoying with the KNS 6400s is that they have a very long cable. One can only hope that KRK Systems will do the world a favor and release some shorter cables soon!