Introduction

The DirectStream DAC MK2 redefines digital audio conversion by using custom FPGA-based processing to convert all inputs—PCM and DSD—into a high-rate DSD data stream. Fully balanced from input to output and upgradable via free firmware releases, it delivers continuously improving performance and sonic detail that traditional DAC chips can’t match.

Design

At its heart, two user-field-upgradable FPGAs implement Ted Smith’s custom D/A architecture, processing all inputs to 20× DSD before converting back down to quad-rate DSD via a passive transformer-coupled output stage. Complete galvanic isolation of every input, output, and power source eliminates ground-loop noise and jitter, while the built-in lossless volume control lets it drive an amplifier directly.

Application

Use it as a reference-quality DAC ahead of your preamp or connect it straight to a power amplifier thanks to its volume control. With dual I²S, dual AES3/XLR, coaxial, optical, and USB inputs—plus balanced XLR and single-ended RCA outputs—it slots seamlessly into any system to reveal hidden layers of resolution, soundstage depth, and musical dynamics.

Technology Overview

• FPGA-Based D/A Processing: All inputs are upsampled to 20× DSD (56.448 MHz) and then reconverted via high-speed passive output transformers for purity and transparency.
• Digital Reclocker & Isolation: Incoming data is buffered and reclocked with zero-loss precision; full galvanic isolation for every I/O prevents noise ingress.
• Synchronous Upsampling: System-wide upsampling to 56.448 MHz (48 kHz family) or 11.2896 MHz (all others) ensures uniform processing and jitter elimination.
• Passive Output Stage: Transformer-coupled analog stage fed by high-current amplifiers maintains bandwidth beyond human hearing with vanishingly low distortion.

Key Features

• Two field-upgradable custom FPGA engines
• 100% DSD-based conversion—no off-the-shelf DAC chips
• Built-in lossless volume control & balance adjustment
• Galvanically isolated inputs and outputs
• Dual I²S, dual XLR (AES3), coaxial S/PDIF, optical (TosLink), USB Type B
• Balanced XLR and single-ended RCA outputs
• Flexible fixed or variable output modes
• Fully symmetric analog signal path

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