@Claritas: Sorry it took a while to get this up, been really busy with other reviews, projects (school), and finals. That said, I've taken the BlueAnt Embrace out of the comparison (if you want to read that comparison, let me know, I can add it in! Let me know ASAP though, I need to send the HP30 back to NAD

).
NAD VISO HP30 vs Buncha' Headphones
The NAD VISO HP30 walks itself into a price bracket that is dense with competition priced right around 230 dollars. The V-Moda XS seems like its most logical competitor price-wise, however, the likes of the B&W P5 S2 (I'll just used P5 for this review) will be the closest in terms of sound signature. With that all said, let's take a closer look at its competition.
NAD VISO HP30
Price: 230 (200 street)
Signature: V-Shaped
Phiaton MS 430
Price: 180 (45 street)
Signature: Neutral
V-Moda XS
Price: 230 (129 street)
Signature: Warm-over-neutral
Bowers & Wilkins P5 S2
Price: 300 (285 street)
Signature: V-Shaped
NAD VISO HP30 vs Phiaton MS 430
The NAD VISO HP30 and the Phiaton MS 430 are really on opposite ends of the spectrum when it comes to sound signature. The HP30 has a V-shape while the MS430 sound neutral in comparison. So the contrast between the two headphones will definitely be strong.
We'll start out with the bass, where these two differ in just about every way. The HP30 has a bass that is boomy in contrast to the MS430s with a strong, thick impact (though it stays within its bounds). The 430 has a smaller, much better controlled punch. In terms of speed, neither is really the fastest, I'd have to say that the MS 430 might have an edge. As for depth, both do provide a bit of depth, but the MS430 has a little more of a subtle approach to it while the HP30 can sound more euphoric in comparison. It's quantity helps it out quite a bit in this area; the 430 can use a little more presence in the deepest lows.
Things take a turn as we dive into the midrange. There definitely is a smoothness to the way the HP30 handles the midrange. Details seem to come a little more effortlessly with the MS 430 due to this. In terms of clarity, however, neither really seem to lack in this department. The vocals, on the other hand take a quick switch. The MS 430 keeps them in-line with the instrumentals (quantity wise) while the HP30 gives it a more forward approach. This also gives vocals a strong dynamic with the HP30.
As we go up into the highs, we do find that the HP30 does take it when it comes to overall quantity. The MS 430 are a little more tame with the amount of treble they give you, though the HP30 still do a better job rendering them. The MS 430 smears some of the treble slightly and almost gets sibilant (though doesn't quite reach sibilance). The HP30, despite having much more quantity, has a little better clarity and presence overall.
The Phiaton MS 430 originally retailed for 180 dollars, 50 dollars less than the HP30. So it makes sense that the NAD would outdo the Phiaton in most categories. However, the MS 430 has dropped greatly in price to being under 50 dollars, so they may be worth a look in terms of value. When deciding between the two, the Phiaton is technically inferior, but does have a more neutral sound signature.
NAD VISO HP30 vs V-Moda XS
The NAD VISO HP30 and V-Moda XS are both priced right at 230 a piece (such a coincidence) so this would be the battle to look for. They both offer a different sound when it comes what signature they wish to provide. Once again, you get a warmer signature offered by the V-Moda XS vs the V-shaped signature of the NAD VISO HP30.
Once again, we'll start in the bass. Once again, we find the NAD VISO HP30 boomy over the XS (I'm sensing a pattern here). The bass is simply bigger on the HP30 than on the XS; that's not to say that the XS doesn't have enough quantity, it definitely does. Both get excellent depth and presence. In general the XS is a little tighter and faster when it comes to the lows while the HP30 offers a stronger, better-defined impact.
As we go into the midrange, we do find that both headphones render the music a little smoother than it should. This does cut into the detailing overall, though the V-Moda do it a less than the NAD. Clarity is strong on both headphones as well. The other main difference is in vocal presentation. The NAD have their way of making vocals a little darker in general. This results in the XS offering vocals with stronger dynamics over the HP30.
Walking up the chain once more, we end up in the treble. Both headphones actually do a terrific job in this area. Detailing and separation, for both the entire treble range, are great with either pair of headphones. There is one thing that should be noted, the HP30 offers more energy and quantity in this area while still being able to maintain high quality as well.
This was probably the battle of battles since both headphones sit at the same price range. An in reality, both are on par with each other, but for different reasons. Personally, I feel the V-Moda XS edges out the NAD VISO HP30 slightly, but preference does play a roll into that. If you're looking for a V-shaped signature, the HP30 is the way to go... Maybe, the Bowers & Wilkins P5 S2 may have something to say about that.
NAD VISO HP30 vs Bowers & Wilkins P5 S2
Speaker company meets speaker company. V-shape signature meets V-shape signature. Who does it better? The pricier Bowers & Wilkins P5 (Series 2) or the NAD VISO HP30, priced at 300 and 270, respectively? This is probably the most interesting of the battles as both of these headphones have such similar signatures.
Oh boy, we've found a headphone that offers more boom than the HP30. The P5 offers a boom that is slightly (and I stress the word slightly) boomier than what the HP30 offers. In terms of presentation, they are playing the same game overall. Good depth comes from both of them as well as presence throughout. Though, I should note that the P5 does have a slight bias on the sub-bass that the HP30 doesn't have; this can backfire on the P5 at times however causing the bass to lose control. In terms of speed and tightness... Who am I kidding? Neither do a great job at that.
We'll move into the midrange and find that the HP30 does do a better job in terms of vocal dynamics. This is the most apparent part to me (keep in mind that this was a weakness of the HP30 against the other headphones). Clarity and detailing is improved against the P5 as well. In reality, what ends up happening is that the P5 sounds like it has a slight veil in the midrange in contrast to the HP30.
Stepping up into the highs, we find very similar presentations once again. Both offering great detailing and separation throughout the region. However, the HP30 does have slightly more quantity and thus more energy throughout this area. This results in a slightly stronger, more dynamic snap as well as sparkle. Neither really gets sibilant or harsh. One thing I will mention is that the P5's treble is much easier on the treble and one that I do prefer. In actuality, however, if you can deal with the extra energy, it's really a wash when it comes to technicalities.
So this one seems like a no-brainer when it comes to winners: the NAD VISO HP30 offers more controlled bass and more dynamic mids. However, when we go up top, it's a matter of preference, they both are technically very strong. I really can't justify spending the extra 70 dollars on the Bowers & Wilkins P5 unless you crucially need the tamer treble.
Conclusions
The NAD VISO HP30 really is a strong contender in this price range, there is no doubt about that. It's able to outclass things under its price range and keep up with things in its price range. Heck, it's able to outclass at least one headphone above its price range. NAD walked into this battle with a V-shaped signature, a V-shaped signature that outperformed the only other headphone in this range that has one... So my conclusions: if you're looking for a neuralish/warmer headphone, get the XS, if you want a little more V in your step, the HP30 is probably the headphone for you.