Pro-Ject Tube Box S2 Phono Preamp Review

I receive alot of questions about the Pro-Ject Tube Box S2 since I used to use it with my main setup. I figured I would update this and bring the review I made a few years ago back to help those folks. In this review, I’m going to dig into the nitty-gritty of its performance, features, and build quality while highlighting its pros and cons.

Design and Build Quality:

The Tube Box S2 sports a sleek, compact design that effortlessly melds into most audio setups. The front panel is equipped with a power button, input gain selector, and a subsonic filter switch, whereas the rear panel accommodates input and output RCA connectors and grounding post. Meanwhile, the dip switches for tweaking impedance and capacitance settings are tucked away at the bottom. 

Performance:

The sound quality always had a warm, captivating, and detailed sound signature. Its dual-mono circuit design guarantees precise channel separation, and although I’ve never used the subsonic filter, it’s there for anyone who wants it. The Tube Box S2 is compatible with both MM and MC cartridges, making it versatile enough for a wide range of turntables. The excellent instrument separation and impressively quiet background create an intimate and immersive listening experience, and I’ve never detected any buzzing across various setups.

Things to Keep in Mind:

1. Limited tube rolling options: The Tube Box S2 comes with two stock ECC83 (12AX7) tubes, which already deliver exceptional sound quality. However, some users might want to experiment with tube rolling to further customize the sound to their liking. Unfortunately, the Tube Box S2 only supports ECC83 tubes and their direct equivalents, restricting the possibilities for tube rolling. I’ve personally swapped the stock tubes with NOS RCA 5751s and, more recently, a pair of NOS matched Mullard tubes.

2. Dip switches for cartridge settings: Adjusting the impedance and capacitance settings on the Tube Box S2 involves tinkering with the dip switches at the bottom, which can be a hassle and time-consuming, particularly for those who enjoy experimenting with different cartridges. A more user-friendly approach would have been a front panel control for these settings. It could also be somewhat intimidating for new users.

Conclusion:

The Pro-Ject Tube Box S2 phono preamp is a stellar performer, delivering warm, engaging, and detailed sound along with a versatile feature set. Its compatibility with both MM and MC cartridges and adjustable impedance and capacitance settings make it a strong contender in its price range. While it does come with a few drawbacks—limited tube rolling options, inconvenient dip switch adjustments, and a higher price point—the Tube Box S2 remains a top-notch choice for vinyl enthusiasts seeking a high-quality phono preamp to elevate their listening experience.