Before I get started. Before the lopsided benchmarks start their way across your screen. Even before I head to the loo, I'd like to say that both devices are wonderful. The Go-DAP for approaching audio and everything like a Swiss Army knife and tackling so many issues at once. The SOLO for single-mindedly attacking SPDIF and analogue output to great effect.
The full comparo between the Go-DAP Unit 4.0 and AlgoRhythm SOLO is up at TouchMyApps. Here will be a summary with perhaps more jargon.
Firstly, I've been a toslink/optical user since the mid 90's when I shrunk my CD collection onto Minidisk. Most of my computer connections, too, are in optical. So, at first, the Solo stymied me because I found that Coax cables were thicker, harder to use portably (and sometimes even on a desktop), and I had to get an optical-coax converter so my Edirol could read the output. Bugger.
But weeks later, I really enjoy the COAX and am building a system around it - a system that I had before, but prior to moving, sold. Bugger.
Summary of the Go-DAP Unit 4.0
The Go-DAP Unit 4.0 is everything. It's a case, a charger, a sync port, a music transport, a headphone amp. There may be more that pops up but I'm hard pressed at the moment to find it. Most of its roles it accomplishes with aplomb. The case fits perfectly for iPhone 4/s, protection all edges with a snug rubber lip. it is much better than its predecessor, the original Go-DAP.
The charging circuit comes in two flavours, a 1500mAh unit, and a 2200mAh unit. I am borrowing the 1500mAh unit. It charges an iPhone about 50% in sync mode, and in amp mode, drives its amp completely with its own battery. Your iPhone will get about 8-9 hours of battery life if paired with the Go-DAP to play music.
Summary of the AlgoRhythm SOLO
You already know this but the SOLO has only two functions: digital or analogue output from a 30-pin iDevice. I've found no device it doesn't work on. I favour the iPod nano 7G because it is small. In fact, all SPDIF benchmarks were done via the iPod nano 7G, even with the Go-DAP. You need an outboard amp or DAC/amp in order to use the SOLO with speakers or headphones.
I paired it with ALO's The National for best aesthetic effect, and many others for similarly good sound. It also works very well with HiFi systems.
That is the glory of digital output.
Bits is bits
I knew this wasn't true back in the MD day because one or two CD players I used played back CD's very different to the recorded MD. They should have been identical in sound. It turned out the optical output they used was sub-par. I think in this comparison, we will find the same thing true. Bits is bits, but how those bits get out, and if they are driven by a DAC and final output device that transfers those bits correctly is of chief concern.
In short, the SOLO exceeds the bounds of 16-bit, while the Go-DAP has a hard time even hanging on. The SOLO clams up in only one benchmark: stereo separation, but I distinctly remember an in/out loop of a perfect machine having the same result. It could be that the SOLO does have poor crosstalk. It could just be that the input device is flawed in one area.
Not every item in the RMAA and square wave benchmarks is audible. For instance, both the SOLO and the Unit 4.0 run nearly flawless square waves, the SOLO ringing slightly less in both high and low frequencies. Frequency roll off in the Go-DAP is audible, but to be honest, it isn't a bad sound. It is less sparkly and less engaging, but it is warmer and softer. It will have its fans.
All tests are hosted in full at TMA.
As with digital, the SOLO outclasses the Go-DAP quite handily. Of course, its line-level output necessitates the use of an amp. The Go-DAP doesn't. its output is also about 5dB louder than the Go-DAP's loudest volume setting. Its digital, too, is about 3-4 decibels louder.
The Venturecraft Unit 4.0 doesn't sound bad. It is warm and powerful. It isn't up to 16-bit, and isn't even as measurably reference-level as an iPod from 2004. But, it provides power, cuts off some of the high frequency bite. It has more hiss than other amps, but not the worst I've heard.
Is it a case of too much done under one bonnet? I'm not sure. But, if I were a K701 or Q702/1 owner, I'd jump for it. In one device, it does everything necessary to power and please those headphones. But, it isn't reference.
The SOLO is. I'd imagine that if the iDevice could play more than 16 bits, it would amaze even at 24 bit word length. Eventually we may see.
Edited by shigzeo - 5/21/12 at 7:44am