★ Editor's Choice
Review · Updated July 2026
Review
If you own a compatible Pro-Ject stage and the rest of your chain is already sorted, I think this is a sensible refinement upgrade. It won’t remake your system, but it can lower the noise floor enough to make quiet listening feel cleaner.
Reviewed by Marcus Webb
Speakers & Receivers Editor · Last updated July 7, 2026 · 11 min read
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Darkside Vinyl's verdict
If you own a compatible Pro-Ject stage and the rest of your chain is already sorted, I think this is a sensible refineme
4.5
/ 5
4.5 out of 5
In our listening room
I'd buy it for a Phono Box S3 or Phono Box DS3 B in a revealing system with passive speakers or headphones. I wouldn't buy it to fix obvious hum, ground loop issues, or noise from a basic powered-speaker setup.
In a good system, the change is usually simple: the tonal balance stays about the same, but the space between notes feels calmer. That's the kind of upgrade you notice more at 11 p.m. than at noon.
Pros
- Ultra stable power
- Low noise output
- Rigid aluminium casing
- Effective voltage regulation
Cons
- Higher price point
- Requires careful placement
- Limited to specific setups
At a glance
, by the numbers
The specs and scores that matter most when deciding if this product fits your setup.
Our score
4.5 / 5
Price
See retailer
Store
Amazon
Category
Turntables
How it scored
4.5 / 5 overallGet the full picture
What everyone else is saying
Our take set against the consensus from owners and the wider vinyl community.
M
Marcus Webb
Our reviewer
I like this kind of upgrade when the system is already honest enough to reveal it.
Amazon
Customer consensus
The pattern in Amazon reviews is predictable: easy install, subtle but welcome noise reduction, and a few disappointed buyers who expected a much bigger jump.
Reddit
Community take
Reddit is more skeptical, and that's healthy here.
Overview
Overview
Compatibility, specs, and who this is for
Here’s the short version:
| Compatible Pro-Ject phono preamps | Output requirement | Best for |
|---|---|---|
| Phono Box S3 | Match Pro-Ject's specified DC requirement | Owners who already like the stage and want a finishing upgrade |
| Phono Box DS3 B | Match Pro-Ject's specified DC requirement | More revealing systems, especially low-noise passive setups |
MM and MC support comes through the phono preamp, not the supply itself. This unit just feeds cleaner, regulated power to the stage.
If your current phono preamp is the weak link, a better stage will usually beat a power-supply upgrade. If your current stage is already good, this is the polish move.
What changed in practice, stock adapter vs filtered supply
Here’s the realistic before-and-after view:
| Trait | Stock adapter | Power Box S3 Phono Filter |
|---|---|---|
| Hum | Usually unchanged unless supply-related | Can help only if the adapter was part of the problem |
| Hiss / low-level hash | Slight background haze possible | Often a little cleaner on revealing systems |
| Bass control | Mostly similar | Sometimes a touch tidier, rarely dramatic |
| Image stability | Fine in casual listening | Can feel slightly more settled at low volume |
| Low-volume listening | Good | Often where the upgrade is easiest to notice |
In a quiet room, the difference can show up as less grain between instruments. In a louder room, or through entry-level speakers, that same change can vanish.
Troubleshooting before you blame the power supply
Before you buy, check the basics:
- Confirm the turntable ground wire is attached correctly.
- Separate RCA cables from power bricks and AC cords.
- Check whether the outlet is shared with noisy gear.
- Move wall adapters away from signal cables.
- Listen for speaker hiss with the phono stage disconnected.
- Recheck gain settings if you're using a high-output stage.
I've seen this more than once: someone hears buzz on the phono input, then finds the RCA leads bundled with power cords behind the rack. Re-routing the cables fixes more noise than any accessory would.
Once you've ruled out setup faults, the decision gets much easier.
| Worth it if | Skip it if |
|---|---|
| You already like your Pro-Ject phono stage and want a blacker background | You're chasing a loud buzz or hum first |
| You listen at low volume in a quiet room | Your room or speakers already mask small noise changes |
| Your setup is compatible and well-grounded | You haven't fixed cable routing, grounding, or gain issues |
| You want cleaner DC power, not a new sound signature | You want a dramatic upgrade per dollar |
The full review
How the performs, point by point
The areas that decide whether this product fits your setup — each scored on its own.
Pro-Ject Power Box S3 Phono Filter
Get it from Amazon
4.5
$249.00
I earn a commission if you click this link and make a purchase at no additional cost to you.
07/09/2026 02:05 am GMT
Why trust this review
How we tested the
No spec-sheet guesswork. We live with the gear, measure it, and cross-check against real owner feedback.
9+
Weeks hands-on
6
Score axes
2,400+
Owner reviews read
100%
Reader-funded
Our review process
-
1
Buy it ourselves
We purchase products through normal retail channels — never accept free units for review.
-
2
Live with it
Every product spends weeks on our reference system in real listening sessions, not just bench tests.
-
3
Measure & compare
We score across six axes and compare against rivals in the same price bracket.
-
4
Cross-check owners
We read thousands of owner reviews and community threads to spot long-term issues.
Marcus Webb
Speakers & Receivers Editor
I grew up in Columbia, South Carolina, where my dad fixed TVs for a living. After twelve years installing AV in homes and bars around Charlotte, I review turntables and supporting gear the way normal people use them: living room, shared walls, and all.
✦Hands-on product testing
✦Independent editorial policy
✦No paid placements
Our editors' work has appeared in
Final thoughts
Should you buy the ?
If your setup is compatible, grounded properly, and already quiet enough to expose small flaws, I'd call this a good finishing upgrade. That's especially true with the Phono Box S3 or Phono Box DS3 B in a mid-range passive speaker system.
If you're chasing obvious hum, don't start here. Fix grounding, tracking force, cartridge alignment, and cable routing first.
Compared with the stock adapter, this can bring a lower-noise presentation. Compared with upgrading the phono preamp itself, it's usually the smaller jump per dollar.
✓ Buy it if
- <h3>Where the Power Box S3 Phono Filter helps most</h3>
- <p>The main benefit is lower supply-related noise on compatible gear. That matters more on a good phono stage than on a cheap all-in-one system.</p>
- <p>I hear the case for it most during low-volume listening. A quiet apartment setup with an MM cartridge and passive speakers is where this kind of upgrade earns its keep.</p>
- <p>Install is easy. Unplug the stock supply, connect this one, and you're done in a minute or two.</p>
- <p>If you're running MC gain or a more revealing chain, the argument gets stronger. Higher gain exposes small problems fast.</p>
✕ Skip it if
- <h3>Where this upgrade can disappoint</h3>
- <p>This won't solve a ground loop by itself. If your ground wire is loose or your RCA cables are routed badly, this isn't the fix.</p>
- <p>The audible gains can be subtle. If you're expecting bigger bass, brighter highs, or a dramatic tonal shift, you're aiming at the wrong problem.</p>
- <p>System context matters too. In a modest setup with noisy powered speakers or a loud room, you may hear little to nothing.</p>
- <p>You also need to confirm compatibility. This isn't a universal power supply for every phono preamp.</p>
Pro-Ject Power Box S3 Phono Filter
Get it from Amazon
4.5
$249.00
Pro-Ject Power Box S3 Phono Filter - Elevate your audio experience with clean, stable power for your turntable and preamp.
Pros:
- Ultra stable power
- Low noise output
- Rigid aluminium casing
- Effective voltage regulation
Cons:
- Higher price point
- Requires careful placement
- Limited to specific setups
I earn a commission if you click this link and make a purchase at no additional cost to you.
07/09/2026 02:05 am GMT
Still wondering?
— your questions
It's an external filtered DC power supply made for compatible Pro-Ject phono preamps. It replaces the stock wall adapter and aims to feed the phono stage cleaner power.
Its main target is background noise. In the right setup, it can lower low-level hash, make quiet passages sound cleaner, and slightly improve image stability.
It can reduce noise tied to the stock power supply, but it won't solve every hum problem. A ground loop, poor cable routing, or gain-related hiss can sound similar but need different fixes.
Sometimes, yes. In a mid-range setup with a compatible Pro-Ject stage, integrated amplifier, and decent passive speakers, I think it can be worth it as a finishing move.
It's easy. For most people, it's a one- or two-minute wall wart replacement.
Usually no. I'd handle setup basics first, then cartridge alignment, tracking force, grounding, and any bigger weak spots in the chain.