If you're both diehard Head-Fi'er and iPhone user, then there's some likelihood that you're familiar with the Head-Fi'er-only conundrum presented by the iPhone's full screen, and that's that most portable amps can't be lashed to an iPhone (using straps or bands, as is most common) without obscuring the iPhone's screen. The options are to find a case specially designed to hold both an iPhone and an amp (and, though there may be ones that fit this description, I'm not aware of them); the other is to use Velcro affixed to both iPhone and amp, which many iPhone-loving esthetes would consider a sort of sacrilege. Actually, now, comes a third option, and a very cool option at that: VentureCraft's GO-DAP, which I first saw at VentureCraft's exhibit at CanJam 2010 (Chicago), and which I haven't seen anything like since.
The GO-DAP is effectively, succinctly described by VentureCraft: "GO-DAP is a portable headphone amplifier for your iPhone 3GS/3G with an integrated battery for longer listening time." Very specifically, the GO-DAP is a beautifully crafted one-piece unit designed specifically for the iPhone 3GS/3G that has a built-in dock cradle for the iPhone that extracts line-out audio from (and delivers power to) the iPhone's 30-pin jack, a dedicated headphone amplifier, and a 1450 mAh rechargeable battery that both powers the amp and provides charging juice to the iPhone. (I've been able to easily shimmy an iPod Touch into the GO-DAP, too, by the way.)
That the GO-DAP takes line-out audio from the iPhone's 30-pin jack obviates the need for a line-out dock (LOD) cable. Keep in mind that many of the good LOD cables can be found at prices ranging from half the GO-DAP's $199.99 MSRP to as much as 1.5x that. When assembling a nice portable rig with an iPhone 3GS/3G (or iPod Touch) at its center, this should be factored into the value equation.
Aside from a battery-check button on its rear (with corresponding battery/charge-related LEDs) and a volume knob, the GO-DAP's only controls are a three-position switch on the front, the three positions being off, charge and sync. In the "charge" mode, the GO-DAP serves up both amplifier and iPhone charging duties. In sync mode, the GO-DAP's amplifier is still active, but the charger gives way to iPhone syncing via the GO-DAP's mini-USB input, the GO-DAP essentially acting as an amp and an iPhone syncing dock in this mode. (The "sync" mode also passes USB power to your iPhone.) If you're not syncing, then "sync" mode means the GO-DAP is operating in amp-on/charger-off mode.
As much as I enjoy the GO-DAP's charger function, I do wish it had one more setting. As it is, the only way to charge the iPhone with the GO-DAP's battery is in the "charge" mode, which also (and always) turns on the GO-DAP's dedicated headphone amplifier. A setting to allow for charger-only mode, without turning on the amp, would be appreciated (and might conserve a little of the GO-DAP's battery life). This is literally one of only two minor nitpicks I have about the GO-DAP (in addition to one rather significant nit to pick, which I'll get to at the end of this review).
As someone who has made a habit of carrying around a portable USB charger and a spare iPhone cable, I find the charge and sync functions of the GO-DAP handy and indispensable, allowing me to leave the dedicated charger and iPhone cable at home when I take the GO-DAP with me (I just carry the tiny little mini-USB cable that comes with the GO-DAP). Spending as much time on the phone as I do (and using a phone without a swappable battery) makes having a portable battry charger not just convenient, but necessary.
The iPhone 3GS/3G is held in the GO-DAP using its cradle's side-gripping rails, and the hold is relatively firm and secure. I've never had my iPhone fall out accidentally, and yet it's easy to remove and put in place--I suspect VentureCraft gave much consideration to getting the fit and grip just right. The only way I've been able to get my iPhone to break free of the GO-DAP (aside from sliding it out as intended) is to hold the GO-DAP/iPhone upside down and shake rather vigorously. Again, however, in my use of the GO-DAP (and I've used it quite a bit), the iPhone has stayed put during use.
As stated earlier, though designed for the iPhone 3GS/3G, I was able to get an iPod Touch (3rd generation) to work just fine with the GO-DAP. However, because the iPod Touch is thinner than the iPhone 3GS/3G, it helps (and seems safer and more secure) to put a little something (to act as a shim) in between the back of the iPod Touch and the GO-DAP. If you're intending to use an iPod Touch with the GO-DAP exclusively, try sticking thick adhesive-backed loop-side Velcro to the GO-DAP dock slide to fill the gap caused by the thinner iPod Touch.
The second of my two minor GO-DAP nitpicks is its recessed headphone jack. Many portable amps have recessed headphone jacks, but the GO-DAP's is recessed more than most I've used. For overwhelmingly most miniplugs, this won't be a problem. In fact, after using many headphones with the GO-DAP, only one plug has been a problem with the recessed jack of the GO-DAP: The 1/4"-to-mini adapter that comes with the Sennheiser HD598/558/518 cannot insert deeply enough to get both channels working properly. Even though it likely won't be a problem for most, a less deeply set jack would be better, in my opinion.
Overall, it is obvious that a lot of thought and care went into the GO-DAP's design, with much consideration given to making sure the GO-DAP doesn't interfere with the iPhone's functions: I snapped several test photos to make sure the iPhone's camera lens is not obscured at all, and it's not; the bottom of the dock has holes that perfectly match the iPhone 3GS/3G's microphone and speaker placement, not obscuring them at all; the iPhone's controls are all easily accessible; and, again, the sync pass-through allows for USB charging and syncing without having to remove the iPhone from the GO-DAP. Also, the GO-DAP is designed to act as an iPhone stand, in both portrait and landscape orientations. Again, overall, the GO-DAP's form factor is exceptional.
The GO-DAP's specifications, as posted by VentureCraft on Head-Fi are:
Output Power: 300mW (16ê)
Signal to Noise Ratio: >= 95 dB (A Weight)
Distortion: <0.009% (10 mW)
Frequency Response: 10 Hz - 120 kHz
Suitable Headphone Impedance: 16ê to 100ê
Power Supply: Built-in 1450mAh/Rechargeable Battery
Op-Amp: OPA2134U (Texas Instruments/Burr-Brown)
Pre-Amp: OPA2338UA (Texas Instruments)
Power-Amp: TPA6130A (Texas Instruments)
Size: W 65mm x H 132mm (including knob) x D 23mm
The GO-DAP in red, which matches up nicely (aesthetically and in terms of sonics) with the
Candy Red Westone ES5 custom in-ear monitors. (Click on the image to see a larger size.)
As intended, and as should be expected, the GO-DAP provides an elegantly packaged way to run the iPhone's line-out to a dedicated external amplifier. If the circuitry is well designed, then we should be able to expect that the advantages that most of us are familiar with, in terms of using a dedicated outboard headphone amp, should also apply with the GO-DAP, only in an outstandingly tidy setup. Is it going to give you the performance of some of the best portable headphone amps by the likes of HeadAmp, Ray Samuels Audio, ALO Audio, TTVJ, iBasso and others? No. Those amps, however, can also cost far more than the GO-DAP, and not give you the unique form and function of it, especially for iPhone users. But are the sonic advantages of bypassing the iPhone's amp for a dedicated headphone amp evident with the GO-DAP to a solid extent? Again, absolutely.
First off, the noise floor of the GO-DAP is good. With most headphones, the GO-DAP will sound as quiet (in terms of self-noise) as the iPhone itself, with no perceptible hiss. However, more sensitive IEMs (in-ear monitors) can reveal a noise floor that is slightly higher than the iPhone's--but, even then, it's low-level enough not to be a problem to me at all. Also, with regard to noise, the GO-DAP does occasionally convey RF noise from my iPhone 3GS, but mostly from wi-fi, and, even then, only occasionally. It seems to happen most noticeably when the iPhone first detects a wi-fi network, and then just briefly during the initial wi-fi handshake, dissipating when the connection's made. It also happens similarly when my iPhone switches from 3G to Edge, and, again, only when it's first connecting to Edge, the noise disappearing once connected. Obviously, when it does happen, it's more noticeable with my IEMs. This occasional RF blipping hasn't been a bother to me, but I think it worth mentioning.
All that said, it's what the GO-DAP does when playing music--in such an elegant, compact, iPhone-charging package--that makes it such a winning product for iPhone 3GS/3G (and iPod Touch) owners. Looking at the specs, you'll see that VentureCraft recommends a headphone impedance range of 16 ohms to 100 ohms, so I tried using many headphones within that range, and one well above it, with the GO-DAP.
With the three custom IEMs I used with it (Westone ES5, JH Audio JH16 Pro, and Ultimate Ears In-Ear Reference Monitor), the GO-DAP's performance was very good. At low volume levels with these IEMs, the difference between the GO_DAP and the iPhone was primarily some smoothness with the GO-DAP, which, in this case, I find a favorable thing, relative to the iPhone's headphone-out. At moderate to loud volume levels (keep in mind I listen at lower volume than most), the GO-DAP's smoothness and ease trumped my iPhone's comparative slight tendency toward edginess. If you're wondering what edge I'm talking about, I'm going to assume you've likely not compared a good dedicated headphone amp to your iPhone's built-in headphone-out. I don't believe it's a matter of a shortage of power on the iPhone's part (certainly not with these sensitive IEMs), but maybe that the loudness simply emphasizes a comparative lack of smoothness--a lack of refinement--from the iPhone's built-in headphone output. Despite my preference for the GO-DAP with these IEMs, I don't know that I'd go so far as to say it's enough to recommend the GO-DAP solely for use with IEMs. But...
If you're like me, and you like to at least occasionally mate your favorite full-size headphones to your portable rig, then the GO-DAP comes into its own even more impressively with some of my full-sized over-ear headphones than with the IEMs I've tried with it. Considering the GO-DAP's recommended headphone impedance range of 16 ohms to 100 ohms, I decided to start by stepping outside a bit, plugging in my 300-ohm Sennheiser HD650 (with ALO Audio SXC Cryo cable, terminated with a miniplug), and was pleasantly surprised. In my experience, plugging the Sennheiser HD650 directly into the built-in headphone output of my iPhone or any of my iPods is an exercise in mostly dissatisfaction, the HD650 not being the easiest headphone to drive. I was pleasantly surprised by the clear sonic advantage offered up by the GO-DAP, versus the iPhone's headphone-out, in driving the HD650. Desktop rig performance? No, of course not. But compared to the iPhone's headphone-out, the GO-DAP definitely maintains more composure and ease with the HD650. Still, the HD650 was not playing to the GO-DAP's sweet spot, but, given what the GO-DAP is, and what it's designed for, I wasn't the least bit surprised and was nevertheless pleased (given what I was working with).
Next came the new Sennheiser HD598, a 50-ohm headphone that has quickly become one of my favorite mid-priced headphones for its high resolution, fun signature, and versatility--I've found it to be a good match for just about anything I plug it into. Now we're talking. Like so many other amps I've tried, the GO-DAP found an eager mate in the Sennheiser HD598. As friendly to headphone amps as the HD598 tends to be, I've also found it to be revealing of differences between them; and the GO-DAP distances itself from the iPhone's built-in headphone-out very nicely with the HD598. One of the HD598's strengths is its imaging ability, capable of being wide without being diffuse. Directly out of my iPhone, the HD598's imaging is substantially less fleshed out than out of the GO-DAP, where more dimensionality was wrung out of the recordings that have it.
When I want to relax, I sometimes listen to recordings of nature sounds by Naturespace (check out their iPhone/iPod app in the App Store, which is what I use, and for which there are exclusive tracks to buy). Using a type of binaural recording method that Naturespace calls "Holographic Audio," the imaging on some of the tracks can, through good systems, be outrageously immersive. (It also helps that Naturespace uses much longer loops, not to mention far better recording quality, than any other such tracks I've been able to find, and I've looked.) One of my favorite tracks is one titled "Loki," which includes the sounds of wildlife and insects at night, rain and trickling water, and rolling thunder--much of it happens out-of-head if your system does it right. "Loki" through the HD598 via the GO-DAP is far more you're there than through the iPhone alone, with more happening outside of the head. It's awesome. Seriously awesome. If you have an iPhone or iPod Touch--and could use an occasional meditative state to calm your mind (or just some gorgeous ambiance to work to)--download the NatureSpace app, and, from there, sample and grab some tracks, starting with "Loki."
The last headphone I used at length with the GO-DAP (at the time of this writing) was another 50-ohm wonder that the Head-Fi community seems unable to stop talking about: The planar magnetic (orthodynamic) Audeze LCD-2. Surprisingly efficient for a planar magnetic headphone, the LCD-2 can even be driven directly from the iPhone's headphone-out. That's not to say that one should do that, only that it can be driven somewhat respectably that way. The GO-DAP very clearly pushes the LCD-2 more adeptly than the iPhone alone, and very portably gives you a taste of why everyone's talking about this headphone. Through the iPhone directly, the LCD-2 still can make beautiful music; but through the GO-DAP's amp, the layers and layers of detail and texture really start to make themselves heard. Track 7 on the Head-Fi/HDtracks headphone system test album Open Your Ears (the track is from David Chesky's "Concerto for Bassoon and Orchestra") is the track we chose to test your system for palpable detail and texture. Through the iPhone directly, it's nice. But, again, through the GO-DAP, the details and textures (which the LCD-2 is able to delivery in copious amounts) do make themselves more evident.
Other headphones I've tried with excellent results out of the GO-DAP, but just not that extensively yet, include the Grado HF-2, SHURE SRH-840, SHURE SE-425, Sennheiser HD518 and HD558, and the HiFiMAN RE-262.
Before I conclude this review, I just wanted to discuss my biggest nit to pick about the GO-DAP. If you can't tell, I dig it so much for what it is and does that I'd like to be able to use it with future versions of the iPhone and/or iPod Touch. That it's so custom-fit to the iPhone 3GS/3G is part of what makes it special, but it also means it won't work with the iPhone 4 and beyond. VentureCraft is planning an iPhone 4 compatible model for release sometime in spring 2011, but it would be fantastic if VentureCraft, with their obvious design acumen, could come up with a model with adjustable fittings to accommodate any full-size iPhone or iPod.
That said, my phone right now is the iPhone 3GS, and I've no plans on updating it to anything else until there's an iPhone on a better network than the one I'm currently on. Rumors of the iPhone on other networks (in the U.S.) have been rampant for the last couple of years. As always, it's right around the corner, say the analysts and tech media pundits. Maybe they're right. I'm not holding my breath. But I'm thrilled I have the GO-DAP whilst I wait.
In a nutshell: Sometimes, on the go, I have to be at my lightest. Sometimes, I have to leave my HiFiMAN DAP behind. Ofttimes, I simply can't pack it, so my iPod Classic lashed to a Ray Samuels Audio Protector also gets left behind. But I always have to have my phone handy--always--and right now that phone is an iPhone 3GS. And since receiving the review sample of the VentureCraft GO-DAP, I have not plugged a single headphone into the iPhone's built-in headphone output, except for the purpose of writing what you read in this review. And that should pretty much sum up how I feel about the VentureCraft GO-DAP.