Pro-Ject Audio Systems
Pro-Ject Phono Box S3 B
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Best Phono Preamps · head-to-head
Pro-Ject Phono Box S3 B vs Rega Fono MM Mk5
A sourced, side-by-side comparison. Pro-Ject Phono Box S3 B is cheaper at —. Every spec and price links to its source.
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Rega
Rega Fono MM Mk5
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Full spec sheet
✓ marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.
| Spec | Pro-Ject Phono Box S3 B | Rega Fono MM Mk5 |
|---|---|---|
| US price | — | — |
| Brand | Pro-Ject Audio Systems | Rega |
| Released | — | — |
| Cartridge support | MM and MC | MM only |
| Gain (dB) | 40/45/60/65 dB, plus an additional +6 dB available via the balanced XLR outputs | 41.4 dB @ 1 kHz |
| Snr (dB) | MM: 103/110 dB(A); MC: 85/90 dB(A) | — |
| Riaa accuracy | <0.3 dB (20 Hz - 20 kHz) | better than ±0.2 dB (100 Hz - 100 kHz) |
| Input capacitance pf | 50/150/300/400 pF selectable | 100 |
| Subsonic filter | 20 Hz, 18 dB/octave rolloff | — |
| Thd percent | MM: <0.001% @1kHz, <0.008% 20Hz-20kHz; MC: <0.005% @1kHz, <0.01% 20Hz-20kHz | — |
| Output level | Balanced XLR and single-ended RCA outputs | 200 mV at 1.7 mV input; 200 ohm output impedance |
Sources — Pro-Ject Phono Box S3 B: project-audio.com (verified 2026-08-12). Rega Fono MM Mk5: rega.co.uk (verified 2026-08-12).
What's the difference between the Pro-Ject Phono Box S3 B and Rega Fono MM Mk5?
Where the two actually differ on the specs we track (5 of 8). Matching specs are omitted.
- Cartridge support: Pro-Ject Phono Box S3 B MM and MC vs Rega Fono MM Mk5 MM only
- Gain (dB): Pro-Ject Phono Box S3 B 40/45/60/65 dB, plus an additional +6 dB available via the balanced XLR outputs vs Rega Fono MM Mk5 41.4 dB @ 1 kHz
- Riaa accuracy: Pro-Ject Phono Box S3 B <0.3 dB (20 Hz - 20 kHz) vs Rega Fono MM Mk5 better than ±0.2 dB (100 Hz - 100 kHz)
- Input capacitance pf: Pro-Ject Phono Box S3 B 50/150/300/400 pF selectable vs Rega Fono MM Mk5 100
- Output level: Pro-Ject Phono Box S3 B Balanced XLR and single-ended RCA outputs vs Rega Fono MM Mk5 200 mV at 1.7 mV input; 200 ohm output impedance