Last week I half-arsedly introduced two accessories made specifically for the iDevice audiophile, the Venturecraft Go-DAP Unit 4.0 and the Cypher Labs AlgoRhythm Solo. Both are able and willing to replace larger, more expensive and decidedly untransportable HiFi gear, but only one is worthy of doing so.
Each decodes information internally, outputting high quality analogue signals. But, neither stops there. Venturecraft’s Unit 4.0 spits out SPDIF over a 3,5mm optical connection. It also protects your iPhone, charges it, and syncs it via a cheap and ubiquitous a mini-USB cable. Remember the original Go-DAP? This is its younger, more capable sibling.
The Solo won’t charge your battery nor protect your iPhone. It’s actually sort of beastly to lug around. But, its glory isn’t its general utility. Its glory is its sound and signal quality. Since it doesn’t harness an internal headphone amp, it spits analogue signal at line-level and SPDIF digital signal over coaxial. It pairs perfectly with the likes of the ALO The National and ALO Rx and many other headphone amps.
For years, we’ve had access to the rather high-quality line outputs of the iDevice. Via 30-pin cables, we’ve been able to hook up high quality portable amps, recording devices, microphones, and sync cables. Then came the Wadia iTransport, a device that sat on your desktop and allowed your iDevice to spit out digital signal to an external DAC. Now, there is a host of such devices.
They why of digital is fairly easy to decipher in a single word: accuracy. While analogue signals sound great, they are prone to distortion, jitter, noise, and theoretically degrade via poor quality cables.
Digital has its own host of problems, but for the sake of brevity, I’ll skip them. The music in your iPod/iPhone is 100% digital. The aim of both the Go-DAP and the SOLO is to keep that signal digital. The Cirrus Logic chips in the iPhone/iPod do a fine job of converting digital signals to analogue, but they can be bettered by external converters.
In the case of the SOLO, they are completely outclassed.
Here’s where the argument rights itself a bit. Since the iDevice already does a fine job of converting digital to analogue, DAC virgins and indeed DAC party girls and guys may not immediately realise the effects. What you pay for is the last few iotas of quality, not a revolution.
However, if you pair your iPhone with the proper outboard amps, you can get both demonstrable and measurable improvement.
Digital signals from both the Go-DAP and the SOLO can be split into balanced signals given the right outboard DAC. Balanced signals in turn, can be read by the proper amp, and plugged into the proper headphone. Balanced headphones are few and far between simply because most require rewiring. Some headphones such as new AKG and Sennheiser models can be paired up with high quality balanced cables without surgery. Some IEMs can, too, but IEM topology, whose balanced armature crossovers are meant to operate differently. Some may indeed be better balanced, but among those that sport passive crossovers, I’ve yet to discover one that retains its original magic.
Single driver headphones are another matter all together. The rather thrifty Einar balanced amp provided more power to the DT880 and better left to right stereo separation. The effect was immediately recognisable at matched volume levels.
If you want to get into the more powerful, higher-end world of balanced headphones or speakers, but want to stay portable, either the Go-DAP Unit 4.0 or the SOLO is your ticket.
This review’s RMAA measurements reflect the performance differences between the Venturecraft Go-DAP Unit 4.0 and the Cypher Labs Algorhythm SOLO. Since these measurements are taken with my equipment, they should not directly be compared measurement-to-measurement to other technical data taken with different equipment. The data represent the ability of the amplification circuit to drive headphones and speakers.
As you can see, the SOLO is flawless. In digital, there is zero deviation from RMAA’s benchmark. You cannot do better.
The Venturecraft Unit 4.0 takes a different approach to playback, which is to roll off the highs from just after 1000Hz. It is an extreme approach that isn’t the effect of load. Unloaded, in both digital and analogue, the Unit 4.0 is unable to sustain anything resembling a proper signal. Because audio is subjective, such a result isn’t a disaster. Many audio makers add their own signature to sound. Personally, I enjoy the sound very much, especially with the likes of the DT880, which are bright to begin with. However, a digital signal should be as close to the original signal as possible, and in this case, it isn’t.
Again, the SOLO sweeps the test. Its noise levels top actually surpass the limits of 16-bit audio at -97,9 decibels. You won’t find better performance in any portable device, and even in home units, higher scores are probably not discernable. When spitting out analogue, noise creeps in and averages -93,1 decibels, again a damn fine score.
The Unit 4.0 fairs well at -94,2 in digital. It doesn’t break the 16-bit barrier, but the difference in digital signals between the two is negligible when feeding outboard DAC units. In analogue, the Unit 4.0 falls to -87,3 decibels. Again, it is a respectable score, but not necessarily so when considering that the iDevice is able to sustain loaded levels up to -91 decibels.
Again, the SOLO exceeds the bounds of 16-bit audio at +96,7 decibels. One wonders how it would fair if playing back higher resolution material. The DAC is capable of it, but the iPhone isn’t.
The Go-DAP still isn’t putting its strong foot forward. At an averaged +63,3 decibels, it puts out the dynamic range of an iPod under heavy load. It actually sounds decent here though, quite excellent for recordings that are heavy on binaural material and harsher sounds.
THD IMD and noise
If there was a more violent trounce party, I don’t know what it is. The SOLO isn’t able to manage the bounds of 16-bit audio for THD+noise, but it does deliver very high quality signal.
The Go-DAP sprouts IMD errors from its digital ports like the Titanic spouted water into the Atlantic Ocean. Its analogue output fairs much better, managing merely the worst output score I’ve tested thus far. The digital output is simple astonishing.
Here, both units perform well within the bounds of my expectation. I’ve found that the original RMAA signal played end to end from other digital outputs never deviates from around -50dB at worst. Why, I can’t tell you, but: both units perform horribly here.
Analogue: both units perform well here, with slight ringing in the high frequencies the sort of low frequency responses you would typically see in high quality analogue devices. Ringing is minimal, though, again, the SOLO outperforms the Go-DAP Unit 4.0. I would suggest that the differences that favour the SOLO aren’t discernible.
Digital: both units perform well, but the SOLO is less plagued by ringing. The Unit 4.0 shows slight, though almost imperceptible ringing in both signal extremes.
NOTE: Take note of the shape and size of the ringing portion. The Square waves are drawn by Sound Studio when recorded in/out via Edirol FA-66. The software doesn’t allow for 100% scale comparisons.
As you can see, the SOLO ran digital circles around the Unit 4.0 in just about every test. Add to that a cleaner analogue signal, and you have a truly pocketable reference level system. Of course, the SOLO necessitates the use of external cables, amps, and a lot more money. It exceeds the bounds of 16-bit in every test but one: stereo separation, and creates a perfect square wave. In its singular purpose, it is nonpareil.
The Unit 4.0 is an amazing device. It charges. It protects. It amps. It spits digital. But, apart from its incredible ability to recharge your iDevice, it does so with a lot of strain. Since it is heavy, a fall to the floor will likely damage it. Its amp is fun, and loud, but has more signal noise and distortion than any iDevice does. Its digital signal is a wonderful accessory that adds functionality to your HiFi, but it isn’t nearly up to the same quality as the SOLO is.
If Venturecraft can fix this with a firmware update, or simply by choosing a more stable DAC, they should do so. For now, SPDIF output seems at best a lazy implementation.
Of course the Go-DAP costs less, charges and syncs syncs, and keeps cables out of the way. There is none like it. And, in case you want to ditch the charging features, Venturecraft have just introduced their next project, the X which acts as a DAC and amp for your iPhone and your computer. Again, it is the first of its kind. Get ready for myriad copycats.
On the Go
This light-hearted audiophile would choose the Go-DAP simply because it charges and has fewer parts to break. Cables are buggers. The SOLO practically requires a case of some sort to keep everything together. And, when packed with an amp, headphones, and all the interconnects you need, it looks like a bomb.
Still, both have their fans. I saw heaps of SOLO stacks at the recent Fujiya-AVIC headphone festival. People use them. People enjoy them. And those people are audiophiles that demand the utmost quality from their portable listening rigs.
Both units work with just about every recent iDevice. The SOLO is just that much more compatible. I’ve had a bugger of a time getting an iPod touch 4G working with the Unit 4.0. The SOLO worked with every 30-pin iDevice I plugged it to.
Why iDevice and external DAC?
Here’s a question I’m sure is asked by many audiophiles who look at devices such as the iBasso DX100, HiFiman, Colorfly C4, etc, and suffer indecision. The simple answer is this: if your music requires gapless playback, perfect navigation, few to no firmware issues, better battery life, and almost no build quality concerns, stick with Apple.
If you want the absolute best, you will have to purchase external DACs/amp for these players anyway. Of course, if you hate Apple, you are probably not reading this article anyway.
I throw music onto my iDevices via iTunes drag and drop. I don’t want to make CUE sheets, worry about WAV compatibility, or poor battery life. I don’t suffer players that can’t play back gapless files. Since I demand that music plays back as simply in my device the same as it does from a CD, there is only Apple.
After nearly 2000 words, my conclusion is very simple, but it hinges on you. If you value compactness and have an iPhone 4/s, there is NO other choice than the Go-DAP Unit 4.0. You still get digital output and fun/powerful sound plus all the other features. The Go-DAP Unit 4.0 is a great device. But, its compromises in output signal quality are severe.
Between the two, the SOLO is the only choice for reference-quality sound. But it gives up is portability. It also requires you to invest in outboard audio components. But then again, you knew that, and you were prepared to invest. To you, only one thing matters: signal quality.
While this seems a lopsided comparison, it is the only sort that is possible. Venturecraft chose to attack all angles, Cypher Labs chose to tackle one. Audio-wise, only one nailed it. That is the Cypher Labs AlgoRhythm SOLO.