Balance. That's my best one-word description of what makes the MDR-V6 so special. It does everything well: the bass-midrange-treble balance is nice and smooth, the sound is spacious, and it's easy to listen to for hours at a time. Isolation from environmental noise is quite decent, and no one near you will hear much sound coming from these headphones.
I first compared the MDR-V6 with another Sony, the $299 MDR-R1. That one has more bass, but it's a softer, less detailed, and mellower sounding headphone, and I preferred the MDR-V6's clarity. The MDR-R1 looks nicer, has a more refined feel, and it's more comfortable. Still, I'd rather listen to the MDR-V6.
Next up, the $199 Audio Technica ATH M50, another popular and well-regarded full-size, over-the-ear headphone that doesn't cost too much. The M50 is hard to beat, and the MDR-V6 put up a good fight.
The M50 had more bass oomph, but the MDR-V6's definition and clarity in the low frequencies were just a wee bit better. In the midrange -- pianos, guitars, and vocals -- the M50 had more body, but the MDR-V6 sounded clearer. The M50 has less forward treble, which I like. I found the MDR-V6's high-frequencies brighter (more forward), but not so bright that they became annoying.
The spacious soundstage I heard from Brian Eno's ambient classic "Music for Films" CD was impressive on both headphones, but when I added it all up, I gave the nod to the M50 for its richer sound and better comfort. However, it's nearly twice as expensive as the MDR-V6.
Comparing the MDR-V6 with the Sony was interesting. The two headphones look almost identical and sound similar, with a few key differences. First, the V6 produces a little more bass, but the MDR-7506 is leaner, and its treble range is accentuated. The MDR-V6 sounds more laid-back and mellower, while the MDR-7506 crisper and livelier. I'd go for the MDR-V6, but others may prefer the MDR-7506.
For the last comparison, I donned my former budget favorite audiophile headphone, the Noontec Zoro, which sounded lean and dynamically constricted next to the MDR-V6. The Sony's extra brawn let it rock harder than the Zoros. No sub-$100 headphone in my experience can touch the MDR-V6's sound quality.
I'm thrilled that Sony never tinkered with or tried to improve the MDR-V6. Not every product needs to be updated every year -- or every few years. When you make a great-sounding headphone that people are still buying, let it be, and that's just what Sony did.
Of course, the V6 can't be considered in isolation, given its very close sibling, the MDR-7506. Comparing the two was interesting; anyone who claims these two look-alikes sound the same should have their hearing tested. First, the MDR-V6 makes more and fuller bass while MDR-7506 is leaner -- vocals sound more immediate, and the treble range is accentuated. As noted, the MDR-V6 is comparatively has a more relaxed sound while the MDR-7506 is more crunchy and alive.
I can't say they are day-and-night opposites -- the two headphones share a similar overall sound -- but the differences are significant, so it's just a matter of picking the one that matches your taste. I'd go for the MDR-V6 -- I highly recommend it -- but CNET Executive Editor David Carnoy, who edited this review, preferred the MDR-7506. And so did CNET editor Matthew Moskovciak.
In other words, these are two excellent headphones that offer distinct sonic differences. It's less about which one is "better" and more about which sound you prefer. But if you value sound quality and comfort, both of these should be at the top of your list when you're shopping for headphones under $100.