Audio T Verdict
The Pro-Ject Phono Box S2 is a particularly useful phono stage if you want more flexibility than a fixed Moving Magnet input without jumping straight into a much larger or more expensive design.
It handles both Moving Magnet and Moving Coil cartridges and, more importantly, gives you meaningful control over the way those cartridges are electrically matched. Four gain settings, four capacitance choices and four impedance options mean the S2 can accommodate a surprisingly broad range of cartridges rather than assuming one setting is suitable for everything.
The adjustments are made with DIP switches underneath the case, so this isn't a model designed for constantly changing settings from your listening chair. Get it configured correctly for the cartridge, though, and its dual-mono circuitry, WIMA polypropylene capacitors, accurate RIAA equalisation and switchable subsonic filter make it a very capable little phono stage.
Pro-Ject Phono Box S2 MM and MC Phono Stage
The Phono Box S2 is a compact phono preamplifier designed for both Moving Magnet and Moving Coil cartridges.
It takes the very low-level signal produced by a turntable cartridge, applies the necessary gain and RIAA equalisation, and produces a conventional line-level output ready for an amplifier, preamplifier or active speaker system.
What separates the S2 from more basic fixed-loading phono stages is its adjustability. Gain, input impedance and capacitance can all be configured to suit the cartridge being used, making it suitable for a much broader range of analogue systems.
- Moving Magnet and Moving Coil compatibility
- Dual-mono circuit configuration
- Audiophile-grade amplification modules
- Polypropylene WIMA capacitors
- Precise RIAA equalisation
- Four gain settings
- 40 / 43 / 60 / 63dB gain
- Four input-impedance options
- 10Ohm / 100Ohm / 1kOhm / 47kOhm loading
- Four input-capacitance settings
- 100 / 200 / 320 / 420pF capacitance
- Switchable 20Hz subsonic filter
- 12dB-per-octave subsonic slope
- 85dB published signal-to-noise ratio
- 0.01% MM THD+N
- 0.05% MC THD+N
- RIAA accuracy better than 0.4dB
- Single stereo RCA phono input
- Turntable grounding terminal
- Single stereo RCA line output
- Bottom-mounted cartridge setup switches
- Front-panel standby control
- Aluminium and metal sandwich casework
- External 18V power supply
- Compatible with Pro-Ject Accu Box S2
- Black or Silver finish
Why Do You Need a Phono Stage?
A turntable cartridge produces a much smaller electrical signal than a conventional CD player, streamer or DAC.
The signal also isn't recorded onto vinyl with a flat frequency response. Records are cut using the RIAA equalisation curve, which reduces low frequencies and increases high frequencies during mastering.
A phono stage therefore performs two essential jobs:
- Amplifies the cartridge signal to a usable line level.
- Applies inverse RIAA equalisation to restore the intended frequency balance.
Once the Phono Box S2 has done that, its RCA output can connect to an ordinary line-level input on your amplifier.
Do Not Connect the Output to Another Phono Input
The Phono Box S2 already performs the required phono amplification and RIAA equalisation. Its output should therefore connect to an AUX, CD, Tuner, Tape or other normal line-level input, not another MM or MC phono input.
Moving Magnet and Moving Coil
The Phono Box S2 is designed for both Moving Magnet and Moving Coil cartridges.
That does not mean MM and MC cartridges all use the same settings. Cartridge output level and electrical requirements vary significantly, which is exactly why Pro-Ject gives the S2 adjustable gain, resistance and capacitance.
Four Gain Settings
The S2 provides:
Pro-Ject identifies 40 and 43dB as typical settings for Moving Magnet and high-output Moving Coil cartridges, while 60 and 63dB are intended for low-output Moving Coil designs.
Why Gain Matters
Different cartridges produce very different output voltages.
A typical Moving Magnet cartridge may produce several millivolts, while a low-output Moving Coil design can produce a fraction of a millivolt.
The lower the cartridge output, the more gain the phono stage generally needs to provide.
If the gain is too low, the turntable can sound unnecessarily quiet compared with your other sources. If it is unnecessarily high, you reduce available headroom and may increase noise or distortion.
Choose Gain From the Cartridge Specification
Start with the cartridge manufacturer's output specification rather than simply selecting the highest setting. A conventional Moving Magnet cartridge will normally use 40 or 43dB, while a low-output Moving Coil cartridge will usually require 60 or 63dB.
Four Input-Impedance Options
The Phono Box S2 provides:
- 10Ohm
- 100Ohm
- 1kOhm
- 47kOhm
47kOhm is the conventional load used by the vast majority of Moving Magnet cartridges and many high-output Moving Coil designs.
Low-output Moving Coil cartridges can require significantly lower resistance, which is why the S2 also offers 10, 100 and 1kOhm.
Which MC Impedance Should You Use?
There is no single correct resistance for every Moving Coil cartridge.
Start with the load recommended by the cartridge manufacturer. If the recommended figure lies between the S2's available positions, choose the closest sensible setting and compare where appropriate.
Four Capacitance Settings
For Moving Magnet and suitable high-output Moving Coil cartridges, capacitance can be set to:
This allows the S2 to be matched more closely to cartridges which specify a particular capacitive load.
Why Capacitance Matters With MM Cartridges
Moving Magnet cartridges can be sensitive to the total electrical capacitance connected to them.
This total includes:
- Tonearm wiring
- Turntable phono cable
- Phono-stage input capacitance
Changing the phono-stage capacitance can alter the cartridge's high-frequency behaviour, so the manufacturer's recommended range is the logical starting point.
What About Low-Output MC Capacitance?
Pro-Ject states that input capacitance is effectively irrelevant for conventional low-output Moving Coil cartridges in this application.
With low-output MC, concentrate primarily on selecting the appropriate impedance and gain.
Cartridge Setup Examples
Pro-Ject's operating instructions give several examples which help explain how the available settings are intended to be used.
Moving Magnet Example
Pro-Ject's Ortofon 2M Red example uses:
- 40dB gain
- 200pF capacitance
- 47kOhm impedance
Low-Output MC Example
Pro-Ject's Ortofon Rondo Red example uses:
- 60dB gain
- 10Ohm impedance
- Capacitance not relevant
These are examples for those particular cartridges, not universal settings for every MM or MC design.
Settings Are Made Underneath the Phono Stage
Gain, resistance and capacitance are configured with DIP switches on the underside of the Phono Box S2.
The arrangement keeps the compact front panel clean but does mean the unit needs to be lifted or turned over when cartridge settings are changed.
Disconnect Before Changing the DIP Switches
Pro-Ject instructs users to disconnect the Phono Box S2 from both its power supply and amplifier before changing cartridge settings.
Both Channels Must Be Set Identically
The internal adjustment switches are provided separately for the left and right signal paths.
Pro-Ject specifically instructs that the settings for both channels should be identical.
If one side is configured differently, the two channels will no longer be operating with the same electrical load or gain.
Dual-Mono Configuration
The Phono Box S2 uses a dual-mono circuit configuration.
The left and right channels have corresponding signal-path components rather than simply sharing every part of the amplification circuitry.
This is also why the underside adjustment switches must be set consistently for both channels.
Polypropylene WIMA Capacitors
Pro-Ject uses audiophile-grade polypropylene WIMA capacitors within the Phono Box S2.
The company specifically highlights these components as part of the S2's upgraded circuit architecture.
Audiophile-Grade Amplification Modules
Pro-Ject also specifies dedicated high-quality amplification modules rather than treating the S2 simply as the basic circuit from the original Phono Box placed into a different enclosure.
Precise RIAA Equalisation
RIAA accuracy is specified at better than 0.4dB from 20Hz to 20kHz.
This describes how closely the phono stage follows the standard equalisation curve used when restoring the frequency balance of a vinyl recording.
Switchable Subsonic Filter
A rear-panel switch activates or bypasses the built-in subsonic filter.
Pro-Ject specifies the filter at:
- Frequency: 20Hz
- Slope: 12dB per octave
What Is a Subsonic Filter?
A turntable can generate very-low-frequency energy which is not part of the music.
Possible causes include:
- Warped records
- Tonearm and cartridge resonance
- Mechanical vibration
- Very-low-frequency rumble
This energy may sit below the normal audible range but can still cause the amplifier and loudspeaker woofers to work unnecessarily hard.
When Should You Use the Subsonic Filter?
If you can see your bass drivers making large slow movements while playing records, particularly warped ones, the subsonic filter is worth trying.
If there is no subsonic problem and the turntable is properly isolated, you may prefer to leave it switched off.
85dB Signal-to-Noise Ratio
The current Pro-Ject specification publishes a signal-to-noise ratio of 85dB.
Noise is particularly important in a phono stage because the cartridge signal requires so much amplification before it reaches conventional line level.
MM and MC Distortion
Pro-Ject specifies:
- MM THD+N: 0.01%
- MC THD+N: 0.05%
The higher figure for Moving Coil operation reflects the considerably greater gain required for a typical low-output MC cartridge.
One Turntable Input
The Phono Box S2 provides one stereo pair of RCA phono inputs.
A separate grounding terminal is available for the turntable earth wire where required.
How Do I Connect the Turntable?
- Disconnect the Phono Box S2 from its power supply.
- Connect the turntable's left and right RCA plugs to the S2 input.
- Connect the turntable grounding lead to the earth terminal where required.
- Configure the underside switches for the cartridge.
- Connect the S2 output to a normal amplifier line input.
- Reconnect power and switch the unit on.
One Line-Level RCA Output
A single stereo pair of RCA outputs connects the S2 to the rest of your system.
Suitable receiving inputs include:
The Output Is Not Another Phono Signal
The S2 output has already been amplified and RIAA equalised. Connect it to a line input, never another phono stage.
Single-Ended RCA Throughout
The Phono Box S2 is a conventional single-ended phono stage.
It does not provide:
- Balanced mini-XLR turntable input
- Balanced XLR line output
- Pro-Ject True Balanced connectivity
If those features are required, the Pro-Ject Phono Box S3 B is the more appropriate model.
Phono Box S2 or Phono Box S3 B?
The S2 and S3 B share the basic goal of supporting both MM and MC cartridges, but they are intended for different levels of system complexity.
Phono Box S2
- One RCA turntable input
- One RCA line output
- MM and MC support
- 40 / 43 / 60 / 63dB gain
- Four impedance settings
- Four capacitance settings
- Underside DIP-switch adjustment
- Switchable subsonic filter
- Compact and straightforward
Phono Box S3 B
- RCA plus balanced mini-XLR inputs
- Two turntables can remain connected
- RCA plus balanced XLR outputs
- True Balanced capability
- Front-panel cartridge adjustment
- Input setting memory
- More extensive MC loading
- Designed for more complex analogue systems
Choose the S2 if you have one turntable and want a highly configurable conventional RCA phono stage. The S3 B becomes worthwhile if you need balanced connectivity, two turntable inputs or more convenient front-panel adjustment.
Works With High-Output Moving Coil Cartridges
High-output MC cartridges often behave electrically more like Moving Magnet designs than conventional low-output MC cartridges.
Pro-Ject therefore groups high-output MC alongside MM when describing the S2's 40/43dB gain and 47kOhm loading options.
Always follow the cartridge manufacturer's own loading specification rather than assuming every Moving Coil cartridge needs the low-impedance MC settings.
Works With Low-Output Moving Coil Cartridges
The 60 and 63dB gain positions and 10, 100 and 1kOhm input loads are provided specifically to accommodate many conventional low-output MC cartridges.
Not every MC design will necessarily be an ideal match, so check both cartridge output and recommended load before purchase.
Can It Be Used With the Debut EVO 2?
Yes.
The Pro-Ject Debut EVO 2 and its supplied Pick it MM EVO can be connected through the conventional RCA input and configured using the S2's Moving Magnet gain, impedance and capacitance settings.
Can It Be Used With Other Turntable Brands?
Yes.
The Phono Box S2 uses conventional RCA phono connections and does not require a Pro-Ject turntable.
The important consideration is whether the cartridge's output level and recommended electrical loading fall within the adjustment range available from the S2.
Aluminium and Metal Sandwich Casework
The compact enclosure uses Pro-Ject's S2 aluminium and metal sandwich construction.
The rigid case provides mechanical protection for the circuit and helps shield the sensitive phono electronics from external electromagnetic interference.
Why Shielding Matters With Phono
Phono signals are extremely small, particularly with low-output Moving Coil cartridges.
Any unwanted noise introduced before or during the high-gain phono amplification stage can become much more noticeable than it would with a conventional line-level source.
Compact 103mm-Wide Design
Despite its adjustability, the Phono Box S2 occupies very little shelf space.
The current Pro-Ject specification gives overall dimensions of:
- Width: 103mm
- Height: 36mm
- Depth: 115mm
Its small footprint makes it easy to position close to a turntable, which can also help avoid unnecessarily long phono-level cable runs.
570g Net Weight
Pro-Ject's current dedicated specification gives a net weight of 570g.
External 18V Power Supply
Power is provided by an external 18V / 500mA DC supply.
The S2 itself is specified at 18V / 85mA consumption.
Why Keep the Mains Supply Outside?
Keeping the mains transformer away from the phono circuit helps physically separate a potential source of electromagnetic interference from electronics designed to amplify very small cartridge signals.
Accu Box S2 Upgrade Compatibility
Pro-Ject currently lists the Accu Box S2 as a compatible upgrade power supply for the Phono Box S2.
The rechargeable Accu Box allows compatible Pro-Ject electronics to operate from battery power rather than directly from a mains-powered DC supply.
This is an optional upgrade rather than something required for normal operation.
Front-Panel Standby Control
A button on the front panel switches the Phono Box S2 between operation and standby.
The blue indicator above the button shows when the unit is operating.
Black or Silver
The current Phono Box S2 is available with:
- Black front panel
- Silver front panel
Who Is the Phono Box S2 For?
The Phono Box S2 makes particular sense if you:
- Need a phono stage for an amplifier without a phono input
- Want something more adjustable than a basic fixed MM stage
- Use a Moving Magnet cartridge
- Use a high-output Moving Coil cartridge
- Use a suitable low-output Moving Coil cartridge
- Want adjustable cartridge capacitance
- Want adjustable MC loading
- Want four gain settings
- Need a subsonic filter
- Only need one turntable input
- Only require conventional RCA connectivity
- Want a very compact phono preamplifier
- Want an official battery-power upgrade route
Key Features
- Pro-Ject Phono Box S2
- MM phono stage
- MC phono stage
- High-output MC compatible
- Low-output MC compatible
- Dual-mono configuration
- Audiophile-grade amplification modules
- WIMA polypropylene capacitors
- Precise RIAA equalisation
- RIAA accuracy better than 0.4dB
- 40dB gain
- 43dB gain
- 60dB gain
- 63dB gain
- 10Ohm loading
- 100Ohm loading
- 1kOhm loading
- 47kOhm loading
- 100pF capacitance
- 200pF capacitance
- 320pF capacitance
- 420pF capacitance
- Underside DIP-switch adjustment
- Switchable subsonic filter
- 20Hz filter frequency
- 12dB-per-octave filter slope
- 85dB signal-to-noise ratio
- 0.01% MM THD+N
- 0.05% MC THD+N
- Stereo RCA phono input
- Turntable ground terminal
- Stereo RCA line output
- Front standby button
- Aluminium and metal sandwich enclosure
- 18V / 500mA external supply
- Accu Box S2 compatible
- 103mm wide
- 570g net weight
- Black finish
- Silver finish
Frequently Asked Questions
Is the Pro-Ject Phono Box S2 still current?
Yes. It remains part of Pro-Ject's current S Line and active phono-stage range.
Does it support Moving Magnet cartridges?
Yes.
Does it support Moving Coil cartridges?
Yes. The available gain and impedance settings allow it to work with many high-output and low-output MC cartridges.
How many turntables can I connect?
One turntable at a time.
What input does it use?
One stereo pair of RCA phono sockets.
Does it have a grounding terminal?
Yes.
What output does it use?
One stereo pair of RCA line-level outputs.
Does it have balanced XLR output?
No.
Does it have Pro-Ject True Balanced connectivity?
No. For True Balanced mini-XLR input and balanced XLR output, consider the Phono Box S3 B.
What gain settings are available?
40, 43, 60 and 63dB.
Which gains are intended for Moving Magnet?
Pro-Ject identifies 40 and 43dB as typical for MM and high-output MC cartridges.
Which gains are intended for low-output Moving Coil?
60 and 63dB.
What impedance settings are available?
10Ohm, 100Ohm, 1kOhm and 47kOhm.
Which impedance is normally used for MM?
Most Moving Magnet cartridges use 47kOhm, although you should always check the cartridge manufacturer's specification.
Does every Moving Coil cartridge use 100Ohm?
No. MC loading varies considerably. The S2 provides 10, 100 and 1kOhm options specifically because different cartridges require different loads.
What capacitance settings are available?
100, 200, 320 and 420pF.
Why is capacitance adjustable?
Moving Magnet and suitable high-output MC cartridges can be sensitive to the total capacitive load presented by the tonearm wiring, phono cable and phono-stage input.
Does capacitance matter with low-output Moving Coil?
Pro-Ject states that input capacitance is not relevant in the same way for conventional low-output MC cartridges.
How are the settings changed?
Using DIP switches underneath the Phono Box S2.
Do both channels have to be configured separately?
The switches correspond to both signal channels and Pro-Ject instructs that both channels must be set identically.
Can I alter the DIP switches while the unit is operating?
No. Pro-Ject instructs users to disconnect the unit from both the power supply and amplifier before changing settings.
Does it have a subsonic filter?
Yes.
Where is the subsonic-filter switch?
On the rear of the unit.
What frequency is the subsonic filter?
20Hz.
What is the filter slope?
12dB per octave.
Why would I use the subsonic filter?
It can reduce unwanted very-low-frequency energy caused by record warps, mechanical resonance and rumble.
What is the signal-to-noise ratio?
Pro-Ject's current dedicated specification states 85dB.
What is the MM THD+N?
0.01% under Pro-Ject's published specification.
What is the MC THD+N?
0.05% under Pro-Ject's published specification.
What is the RIAA accuracy?
Better than 0.4dB from 20Hz to 20kHz.
Does it use dual-mono circuitry?
Yes. Pro-Ject specifies a dual-mono configuration.
What capacitors does it use?
Pro-Ject highlights audiophile-grade polypropylene WIMA capacitors.
Can I connect its output to my amplifier's phono input?
No. Connect the S2 output to a conventional line-level input such as AUX, CD, Tuner or Tape.
Can I use it with active speakers?
Yes, provided the active speakers have an appropriate analogue line input and their own volume control. The S2 itself is not a preamplifier or volume controller.
Does the S2 have volume control?
No.
Does it have a headphone output?
No.
Does it have USB?
No.
Does it have Bluetooth?
No.
Can it digitise records?
No. It is an analogue phono preamplifier.
Does it work with non-Pro-Ject turntables?
Yes. It uses conventional RCA phono connections. The cartridge simply needs to be compatible with the available gain and loading settings.
Can I use it with the Debut EVO 2?
Yes. The Debut EVO 2 and its Pick it MM EVO cartridge can be connected using the S2's conventional MM settings.
Can I use a low-output MC cartridge?
Yes, where the cartridge's required gain and loading are compatible with the S2's 60/63dB gain and 10/100/1kOhm impedance options.
Can I use a high-output MC cartridge?
Yes. Pro-Ject groups high-output MC cartridges alongside MM when describing its lower gain and 47kOhm loading settings.
What is the enclosure made from?
Pro-Ject describes the S2 housing as an aluminium and metal sandwich construction.
How large is it?
The current Pro-Ject specification gives 103mm wide, 36mm high and 115mm deep.
How much does it weigh?
570g net according to Pro-Ject's current dedicated product specification.
What power supply is included?
An external 18V DC / 500mA supply.
What is the unit's operating consumption?
Pro-Ject specifies 18V / 85mA.
Does it have standby?
Yes. The front-panel button switches between operating and standby modes.
Can the power supply be upgraded?
Yes. Pro-Ject currently lists the Accu Box S2 as a compatible upgrade power supply.
What finishes are available?
Black and Silver.
What is the difference between the Phono Box S2 and S3 B?
The S2 is a conventional single-ended RCA phono stage with underside cartridge adjustment. The S3 B adds a second balanced mini-XLR phono input, True Balanced capability, balanced XLR outputs, front-panel adjustment and separate memory for two connected turntables.
Related Pro-Ject Products
Why Buy the Pro-Ject Phono Box S2 From Audio T?
The Phono Box S2 gives you plenty of adjustment, but those switches are only useful if they are set correctly for the cartridge. Gain, resistance and capacitance all need to be considered alongside the cartridge manufacturer's own specification rather than simply choosing settings by trial and error.
Audio T can match the Phono Box S2 to your existing Moving Magnet or Moving Coil cartridge, configure the underside switches correctly and help you decide whether the S2 offers everything you need or whether a more advanced model such as the balanced Phono Box S3 B would be worthwhile.
- In-store demonstrations
- Moving Magnet cartridge matching
- Moving Coil cartridge matching
- High-output MC guidance
- Low-output MC guidance
- Gain setup
- Input-impedance setup
- Capacitance matching
- DIP-switch configuration
- Subsonic-filter advice
- Turntable grounding guidance
- Phono cable advice
- Accu Box S2 upgrade guidance
- Future cartridge upgrade planning
- Phono Box S2 versus S3 B advice
- Ongoing after-sales support
Contact your local Audio T store to arrange a demonstration or discuss the correct Phono Box S2 gain and loading settings for your cartridge.