KRK Systems has updated its KNS line of studio headphones with the KNS 6402 and KNS 8402, both with enhanced sound quality, isolation and durability. Both models are closed-back circumaural (over and around the ear) designs with the KNS 8402 ($149 MSRP) updated for pro studio use and the KNS 6402 ($99 MSRP) more suited for home studio production and stereo music enjoyment.

All the KNS headphones come in matte black only and are made using an impact-resistant plastic material that makes them super lightweight. The cables, head and premium leatherette ear cushions are easily field-replaceable, including the in-line volume control that uses a 'long life' fader, which connects between the headphones and the supplied cable using 3.5-mm stereo plugs. You can easily remove the in-line volume control altogether.

I tried out the KNS 8402 headphones and immediately liked the self-aligning, sprung stainless steel yoke system in the headband that easily adapted to my head and retained that adjustment when I took them off.

The memory foam ear cups rotate up to 90 degrees and I found it more comfortable to not allow the center of the headband to touch the top of my head. There is a gap in the center of the headband, making them feel nearly weightless. They still hugged my head comfortably to block out sounds with up to 30dBA of isolation.

The KNS series phones use 40mm dynamic drivers with neodymium magnets; the rated impedance of 36 Ohms. They are rated at 0.1% total harmonic distortion while handling 500mW per driver. Sensitivity on the KNS 8402 is 97 dB SPL @ 1mW with maximum SPL of 124dB. Frequency response is specified as 5 Hz to 23 kHz.

For all my sonic testing, I used my musicians' cue system that uses a Simon Systems CB-4 Cue Box powered by a 100-watts/channel Hafler stereo power amp. I also tried my secondary cue system that uses a small Aphex Systems HeadPod 4 4-channel amplifier with good results. In addition to the KNS 8402s, I kept three other sets of phones plugged into the CB-4 with volumes matched, and I played different kinds of music, as well as individual tracks (drums, bass, guitars, etc.) out of Pro Tools. The KNS 8402s were definitely the lightest.

Overall the KNS 8402s are neutral-sounding: not overly bright or bottom-heavy as compared to my more expensive audiophile models. They are smooth in the mid-range and not as abrasive as some other dynamic sets.

I am looking for a tight seal, which becomes extra important when five or six backing vocalists are singing around a hot mic. A studio might buy a dozen of these headphones for just that purpose. Once the KNS 8402s were properly fitted on a singer's head, the ear cushions did a good job of sealing against leakage.

I was initially a little suspect of an in-line volume control on studio headphones. It could be "another point of failure," but that little fader stays wherever it is set and the teardrop shape doesn't catch on clothing.

If all headphones are fed from the same line, the in-line volume control becomes a necessity. Some backing singers like it louder than others in the same group. When the mini-fader is full up, it is the same volume as with the control removed--there is no difference in sound quality with or without the in-line module in play.

I liked the KNS 8402's wide frequency response, dynamic range, stereo imaging and consistent voicing. These would be a smart buy for a new studio looking to stock their headphone collection with well-made, sturdy and good-sounding units.