Achieving great sound quality with a music server is mainly about two things.
The first factor is the minimisation of noise interference. Sound quality is diminished if high frequency noise sits on top of (is at a higher frequency than) the bit rate of the digital signal. Why? Because it creates uncertainty for the digital receiver in your DAC, about the transitions between bits. It is important to appreciate that a digital signal is ideally a perfect square wave, and that this means there is a need for low noise interference up to very high frequencies, well beyond the bit rate, in order to “square out” the wave.
If we were talking about just transferring data from one device to another, then the noise only needs to be below an unchallenging threshold that enables the bits to be read accurately. But we are not talking about just moving data from one point to another. We are talking about playing a digital audio signal, and the integrity of the signal, not just the bits, impacts the performance achievable by the DAC. If DACs were perfect, then perhaps music servers wouldn’t have to be. But with real world DACs the difference between servers is easily heard.
The Antipodes EX and CX are both designed for extremely low noise, but importantly, this is achieved by minimising the noise that is created, rather than filtering noise after it has been created. Filtering noise above the bit rate is used by most of our competitors, but it means reducing the squareness of the wave, and therefore the precision of the signal. A square wave is generated by first generating the sine wave version of the signal and then adding several harmonics above the signal to square it out. If you attenuate the higher harmonics then you reduce the squareness of the wave.
In our view, the first factor – minimisation of noise interference – is critical. Without adequately addressing it then the timbre of voices and instruments will be unnatural, and typically harsh. Addressing it by minimising the noise generated, as opposed to filtering it, leaves the immediacy and life in the music intact. When noise filtering is applied we typically hear pleasant tonality but which fails to be musically engaging. For this reason both the EX and CX employ state of the art techniques to minimise creation of noise interference with the digital signal, without any noise filtering.
The second factor is minimisation of contention between processes. This is why so many high-end music servers use Linux, since you can build your operating system up from the ground to run only the services you need and to give suitable priority to the processes.
To recap, all Music Server playback requires three steps: a Server app, a Renderer app, and a DAC stage. The optimum solution is to have three independent devices with each performing one of the tasks. But below a certain price level, it can be better to include the Renderer in the same device as the Server (as we do with both the CX and the EX), or to include the Renderer in the same device as the DAC (as is done when your DAC has an Ethernet input).
The optimum hardware for the Server app is quite different from the optimum hardware for the Renderer app, and this is why the EX and CX are different, and why they are both our best devices. The lower-priced EX is an excellent Renderer with a very good but low-powered Server capability. The EX excels in musicality. The higher-priced CX is an excellent Server with a very good Renderer capability. The CX excels at transparent detail resolution.
The CX+EX Solution is to run the Server app on the CX and the Renderer app on the EX and connect the two with a short, high-quality Ethernet cable. The CX+EX Solution not only combines the transparency of the CX with the musicality of the EX, the synergy further improves both of these qualities. There are no easy shortcuts without trade-offs. To get the best audio quality, both the Server and the Renderer need to be of very high quality.
Antipodes does not make a lower-priced two-box solution for the simple reason that the one-box EX or CX provide better sound for the price, plus provide you with an simple upgrade path of adding the other model later to reach the CX+EX Solution.