Audiophiles looking for high-end vinyl playback without mortgaging the house can now turn to Pro-Ject’s latest phono stages. The premium Tube Box S3 B is a tube-based balanced unit that blends high-end tech with a surprisingly compact footprint and a wide range of connectivity options, promising to “raise the bar in the premium analog market.”
At its heart is a symmetrical discrete gain stage that, paired with a balanced-ready turntable, keeps noise low and musical detail intact—proof that balanced design doesn’t have to come with a wallet-crushing price.
Pro-Ject has long been leading the charge in the entry-level audiophile turntable market, and the Debut Pro B and X2B models are proof of that. We’ve reviewed both rather favorably, noting their solid build quality, precise tracking, and excellent sound for the price. It makes sense that the brand is bringing the same attention to detail and thoughtful design to the Tube Box phono stages, delivering performance that appeals to both newcomers and seasoned vinyl listeners.
Pro-Ject has been on a roll in 2025, rolling out a string of releases that span turntables and electronics alike. From the E1.2 and the Peanuts 75th Anniversary table to the AUTOMAT 1.2, the AC/DC edition, and a broad range of new electronics, the brand shows no signs of slowing down. It’s a busy year that reinforces Pro-Ject’s knack for combining style, innovation, and solid performance across their lineup.
Pro-Ject Tube Box S3 B
The Tube Box S3 B provides a wide range of gain options, from 40–65dB, making it compatible with both moving magnet and moving coil cartridges. Control switches let you select inputs or toggle the subsonic filter, which Pro-Ject designed to simplify everyday use.
This is a serious piece of kit for anyone who wants a tube phono stage without gimmicks. Balanced 5-pin mini XLR inputs and full XLR outputs keep the signal clean, while the symmetrical, discrete gain stage handles both MM and MC cartridges.
Two user-replaceable ECC83 tubes sit at the heart of the design, backed by a dual-mono layout and semi-passive RIAA equalization for low noise and minimal distortion. Settings are accessible right from the faceplate, and the aluminium casing keeps interference at bay. Available in silver or black and made in Europe, it’s the kind of well engineered gear that makes you nod and mutter, “Finally, someone got it right.”
Tube Box S3 B – Technical Specifications
- Tube Assembly: 2x ECC83 (12AX7)
- Input Impedance: 10, 50, 100, 1k, 47k Ω
- Input Capacitance: 50, 150, 300, 400 pF
- Gain (+6dB via XLR Out): 40, 45, 60, 65 dB
- Signal-to-Noise Ratio (MM, 40dB): 97dBV / 105dBV (‘A’ weighted)
- Signal-to-Noise Ratio (MC, 60dB): 83dBV / 88dBV (‘A’ weighted)
- THD at 1 kHz: <0.005% MM, <0.01% MC
- THD (20Hz–20kHz): <0.1% MM, <0.03% MC
- RIAA Equalization Accuracy: <0.4dB (20Hz–20kHz)
- Subsonic Filter: 20Hz, 18dB/octave
- Inputs: 1x 5-pin mini XLR, 1x pair RCA phono sockets
- Line-Level Outputs: 1x pair RCA, 1x pair XLR
- Power Supply DC: 18V / 1000mA
- Power Consumption: 18V / 800mA DC, <0.5 W standby
- Dimensions (W x H x D): 206 x 81 x 153 mm (164 mm with sockets)
- Weight: 1010 g (without power supply)
Pro-Ject Tube Box E: Compact, Fully Discrete Tube Phono Stage
For those seeking a more affordable entry into tube phono stages, the Tube Box E offers a fully discrete dual-mono design with adjustable gain, capacitance, and impedance. It supports both moving magnet (MM) and moving coil (MC) cartridges, and includes a front-mounted subsonic filter for added control.
The Tube Box E is housed in a metal enclosure to minimize interference and vibrations, with an aluminium front panel and gold-plated RCA sockets. Dual ECC83 tubes are user-replaceable, allowing for future tube rolling. Based on our experience with other Pro-Ject phono preamps in this price range, we suspect the Tube Box E will offer a warmer, softer presentation.
Tube Box E – Key Features
- Compatible with MM and MC cartridges
- Two-part RIAA equalization (passive/active)
- Fully discrete circuit design without OpAmps
- 2x ECC83 tubes (replaceable)
- Front-mounted subsonic filter
- Front-mounted gain control
- Ultra-low noise FET input stage
- Dual-mono design for channel separation
- Polystyrene capacitors where possible
- Gold-plated RCA in/out
- Multiple internal power supplies
- Well-filtered high-voltage anode supply
- Aluminium front panel, full metal enclosure
- Available in silver or black
Tube Box E – Technical Specifications
- Tubes: 2x ECC83 (12AX7A)
- Input Impedance: 10 Ω, 100 Ω, 1 kΩ, 2 kΩ
- Input Capacitance: 47pF, 147pF, 267pF, 367pF, 487pF, 587pF / 47 kΩ
- Gain: 40 dB, 43 dB / 50 dB, 60 dB, 63 dB
- Noise Floor: 77 dB (A-weighted) at 40 dB gain; 65 dB (A-weighted) at 50/63 dB gain
- THD: <0.03% at 40 dB gain; <0.07% at 50/63 dB gain
- RIAA Accuracy: ±0.5 dB (20 Hz – 20 kHz)
- Subsonic Filter: 20 Hz, 18 dB/octave
- Inputs: 1x pair RCA/phono sockets
- Outputs: 1x pair RCA/phono sockets
- Power Supply: 18V / 1000 mA DC (external, country-specific)
- Power Consumption: 470 mA DC, <1 W standby
- Dimensions (W x H x D): 103 x 73 x 131 mm
- Weight: 450 g (without power supply)
The Bottom Line
The Pro-Ject Tube Box S3 B and Tube Box E phono stages both offer flexible, well-engineered solutions for vinyl playback. The S3 B delivers high-end features including a fully balanced design, dual-mono circuitry, and adjustable gain for both MM and MC cartridges, making it suitable for more demanding setups. The Tube Box E provides similar versatility in a smaller, more affordable package, with a fully discrete dual-mono design and adjustable settings that cover a wide range of cartridges.
Both units are built with interference-resistant metal enclosures and replaceable ECC83 tubes, ensuring long-term reliability and adaptability. While the S3 B targets the premium end of the market, the Tube Box E enriches Pro-Ject’s lineup with a cost-conscious phono preamp option that is likely to offer a warmer, softer sound based on the brand’s track record.
For more information: project-audio.com