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Pro-Ject Phono Box S3 B Balanced & Discrete MM/MC Phono Preamp

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  • $ 499

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At Pro-Ject, balanced connections were exclusive to our RS range of products until now. The Phono Box DS3 B model offers some of the high-end features of the Phono Box RS2 at an affordable price and trusted Pro-Ject quality. One of those is our new True Balanced Connection.

High-End Features and Limitless Loading Options

The Phono Box DS3 B employs a steel chassis enveloped by aluminum panels. This construction offers very high rigidity and isolation against interferences, which is essential for the new technology inside. Magnetic wooden side panels are available separately as add-ons. You can connect up to two turntables simultaneously – all parameters for each input get stored in the memory. Perfectly match the Phono Box DS3 B to a wide variety of cartridges. Load impedance can be set continuously via a potentiometer, a system invented by Pro-Ject Audio Systems, to adjust the impedance during playback and assess the impact of different loading options in real-time. No other manufacturer implements this feature as elegantly!


The Phono Box DS3 B incorporates a true, fully balanced gain stage design. Whether you're using a single-ended RCA or balanced connection, both times the fully symmetrical gain stage can optimize the signal-to-noise ratios, feeding the fully passive and discrete RIAA equalization stage with the cleanest signal to work its magic on. Entirely split passive equalization allows for better impedance matching and lower deviation from the ideal RIAA curve. The Phono Box DS3 B uses fully discrete audio circuitry. A discrete circuit is composed of disparate, individual electronic components, also called discrete components. Years of experience have proven that even the best Op-Amps do not come close to the neutral, natural, dynamic, and vivid presentations of discrete circuit.


  • 5-pin mini XLR balanced input
  • Balanced XLR outputs
  • Fully symmetrical & discrete gain stage
  • Setting easily adjustable on faceplate
  • MM & MC capable
  • Dual-mono design
  • Semi-passive RIAA equalization
  • Low noise / low distortion
  • Aluminum enclosure protects against interference


  • Input impedance: 10, 50, 100, 1k, 47k ohms
  • Input capacitance: 50, 150, 300, 400pF
  • Gain (+6dB using XLR Out): 40, 45, 60, 65dB
  • SNR MM (40dB): 103dBV, 110dBV (‘A’ weighted)
  • SNR MC (60dB): 85dBV, 90dBV (‘A’ weighted)
  • THD at 1kHz: <0.001% MM, <0.005% MC
  • THD (20Hz-20kHz): <0.008% MM, <0.01% MC
  • RIAA equalization curve accuracy: <0.3dB / 20Hz-20kHz
  • Subsonic filter: at 20Hz with 18dB/octave
  • Input: 1x 5-pin mini XLR / 1x pair RCA phono sockets
  • Line-level output: 1x pair RCA, 1x pair XLR
  • Power supply DC: 18V/500mA
  • Power consumption: 18V/170mA DC, <0.5W in standby
  • Dimensions: 206 x 55 x 153mm (164mm with sockets)
  • Weight: 930g without power supply

WARNING: California Residents - Proposition 65. This product can expose you to chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to



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