Zero 09 Version DAC/Amp

Review:  Zero 09 Version

Item: Amplifier (Headphone)

Price: £120

The Zero is a headphone amp made in Hong Kong, there really isn’t much info on manufacturer or anything else for that matter. The amps come with a couple of different options for op amps and inputs. On the op amp front the choices are OPA2604, the cheaper model, and OPA627 the more expensive of the two. For inputs on top of digital coaxial and digital optical it’s possible to have a USB DAC added, great for old computer systems and laptops.

Having heard some good things about these amps and seeing as it has an inbuilt DAC, for the price I was naturally curious and took the plunge. I’ve opted for the OPA627 model with USB in order to use with my netbook.

Zero 09 Version

Appearance, Accessories and Build.

I’m not going to lie, being an import from the far east I had my concerns about how cheap quality the components would be. The outside appearance is fantastic and really looks more professional than toylike, the volume knob feels sturdy as do the 3 smaller buttons. It’s not without fault though and I’ve found that almost every time I try and turn the amp on the power button doesn’t lock in and the amp turns off again, likewise the digital coaxial input on the back is wonky, I don’t think this would cause any issue though.

Accessory wise the box contained manuals in both Chinese and (badly) translated English; I could fathom the instructions after a few reads but to be honest I didn’t read them at first and had no issues, it’s mostly common sense. Also included is a mains cable - for Europe not for Britain - a 1m USB B type connection and a 1m optical S/PDIF connector.

Internally the construction is as good as most major amps I’ve seen the inside of (surprisingly a lot, I used to repair them), one of the things I especially like is that the op amps aren’t directly soldered to the board but instead have used a DIL (an IC holder, so to speak) which will allow easy swapping of op amps should you want to.

Zero's internals

Sound Quality.

Not a great deal of specs for this amp are available, what I have managed to find is that it supports 24bit audio at 192khz over optical or coaxial and 16bit audio at 48khz over USB. The signal to noise ratio is rated at 105db, bear in mind that anything over about 93db is marketing hype realistically as CDs are rated at 93db. Frequency response is rated at 20-30,000hz so will cover the average human hearing range. Now that’s covered I’ll just mention most of these values don’t really count for much as most amps are rated around the same or inflated to give a higher value (and thus more marketing potential), the hearing test is what’s most important.

There is a misconception around what the role of an amp is, most people assume it’s simply to amplify the volume however a good quality amp should be bringing out details in the audio and improving the general sound quality you hear, an example is a pair of headphones which have distorted bass, using an amp should pick the bass up and give it detail rather than just being a muddy mess, of course the headphones have to be capable of that just as much as the amp has to be capable of driving the headphones, it’s all a balancing act but one which can really pay off.

Normally being both a DAC and amp I’d review both parts separately, however the Zero only accepts digital inputs so this isn’t possible. The comparisons I’ll be using due to this are with a Xonar DG sound card which has a built in headphone amp and my Harman/Kardon AVR which has a headphone amplifier built in, albeit not as powerful as a dedicated headphone amp.

From what I can tell the USB and S/PDIF DACs are separate circuits therefore I’ll be reviewing each one separately, starting with the S/PDIF (AKA digital optical).

Turning on the amp, plugging in my DT770s and listening to Natalie Walker’s Urban Angel 2 things were immediately apparent to me; the lack of hiss and how smooth the sound is. Now when I say lack of hiss most people probably think it’s extremely quiet and you can’t hear it with music playing, what I actually mean is there is no audible hiss what so ever at the volumes I would listen to music, it becomes audible with no music playing at around the 1/2 volume mark but the ringing in your ears at this volume would be more apparent I’m sure. For the smooth sound all I can say is I can’t hear any distortion at all common with cheaper DACs, no spiking at certain frequencies and the audio is warm yet accurate, acoustics sound beautiful while bass is deep and clean.

Over time I’ve noticed the sound change subtly, high frequencies are becoming more apparent, not to the point of being harsh or over powering but I can hear more detail than initially. Soundstage which was initially not much larger or accurate than my H/K have over time expanded becoming more accurate and significantly more pleasing, admittedly on a number of occasions when I’ve not been paying attention I’ve forgotten I’m wearing headphones and thought my speakers are in fact playing (which is ridiculous considering they aren’t even connected to anything right now)! Just to clarify the amp doesn’t have Dolby Headphone or Binaural DSPs to create a wide sound stage or to emulate speakers and headphones still sound like headphones, but every so often...

Testing the Zero with my Beyers alone would be unfair so I decided to pit it against my Goldring DR150s which are renowned for being great headphones unamped but don’t really get much improvement from an amp, the improvement is there but subtle and in most cases won’t justify the extra cost. My Xonar DG gave minor improvements to the DR150s however my H/K 2550 didn’t do much to improve it at all, the Zero however had some success, again it’s subtle compared to the Beyers however it’s definitely there, the mids became more detailed and acoustics again had that lovely feeling, the bass and trebles improved slightly but was almost imperceptible, the soundstage also increased in size to a small degree. Sound was significantly cleaner than with the DG however I base this entirely on the DAC as the sound was cleaner with the H/K DAC too.

 

How does the USB fair I hear you ask? I went specifically for this model for use with my netbook which has poor onboard audio and no S/PDIF outputs. I should note that my netbook (Samsung NC10) has both XP and Ubuntu 10.10, but I basically only use Ubuntu. I was relieved to find that the USB DAC worked flawlessly in Ubuntu without having to do anything, it was all plug-n-play.

The USB DAC sounds very similar to the S/PDIF DAC with the exception of lesser bass response, this like with the rest of the amp might improve as it’s used however as of writing this review I’ve only used it for about an hour.

On the volume front I’d be surprised if anyone can have their Zero at full volume, with my relatively quiet DT770s I can only go as far as 1/4 volume, pushing to 3/8 begins to get to ear hurting levels and half is beyond me. With my DR150s I barely have to have the volume on at all.

There is one aspect of the Zero which I haven’t tested yet and that would be the preamp circuit, unfortunately I have way of testing this at the moment as I had to remove my speaker amp in order to use the Zero, in a few weeks when I’ve made space for my new speakers and my amp I’ll test the preamp capabilities and update.

Conclusion.

If you haven’t already guessed I’m absolutely stunned at how good the Zero is for the price, the DAC in my opinion is better than anything else I’ve heard and the amp brings out details I never knew existed and it just keeps getting better. However as with everything it does have its downsides, the ones which really stick out to me are the lack of analogue in which will be a deal breaker if you’re the type who uses old equipment and wanted to pair it up with a cheap headphone amp, or if you plan on using it with a portable device, it’s also not a neutral amp with the emphasis on the mids, bass and treble can seem a little recessed in comparison. The expanded soundstage might turn some people away too as one of the attractions of headphones is the immediacy they produce over speakers, while nothing like using Dolby Headphone the soundstage is larger than without and some of that immediacy is lost. If you know your headphones are renowned for improving with an amp you really should look into buying the Zero as for the price it really is a stunning piece of equipment.