Two boxes almost always beat one. The exception is when someone designs the one box like it was really two.
The trouble with most all-in-one streamer/DACs is proximity. The streaming section is a small computer — processor, memory, Wi-Fi radio, network chips — switching at radio-frequency rates and generating noise on its power rails and ground plane. Put that computer inches from the analog output stages that are trying to reproduce music at whisper-quiet levels, share a power supply between them, and share a ground plane, and you've handed the analog side a fight it didn't need to have.
Separates solve the problem by force. The separate streamer, like our AirLens, lives in its own box with its own supply and its own ground. The DAC lives in its own box with the same. When the digital signal crosses between them — over USB, coax, I2S, or a network protocol — it does so with a clean handoff and no shared noise. Every dollar the DAC didn't spend on network chips or Wi-Fi radios went into analog stages, clock circuitry, and output filtering. That's why a good separates approach tends to outperform a comparably priced all-in-one.
The real lesson isn't that two boxes are magic. It's that the discipline two boxes enforce is what actually delivers the sound. Galvanic isolation between the digital and analog sides. A dedicated power supply feeding the streaming section, isolated from the analog rails. Grounds that don't touch until they absolutely have to. When a designer applies those disciplines inside a single chassis, an all-in-one can perform like separates. It just doesn't happen often, because doing it properly costs almost as much as building two products.
Our PMG 512 DAC has a built-in streamer, and it's built exactly that way — galvanic isolation between the streaming section and the analog section, a separate power supply feeding the streamer, isolated grounds.
Internally it's a two-box design that happens to share one chassis. That's why it works, and it's why we could build it that way in the first place: because we understood what the two-box approach was actually solving, and made sure to solve the same thing inside the one.
Separates are the right answer, even if they are in the same box.
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