Audio T Verdict
The Naim NAC 552 with 552 PS DR is a complete two-box flagship preamplifier system. The sensitive control and audio circuitry sits in the NAC 552 chassis, while the large transformer, rectification and discrete regulation are isolated in the matching power-supply enclosure.
This package includes the dedicated 552 PS DR required to operate the NAC 552. It does not use a 555 PS DR, and there is no NAC 555 model. The two boxes are connected by the supplied NAC 552 Burndy and directional 5-pin SNAIC cables.
Six assignable source selections, separate listen and record banks, DIN and RCA compatibility, two unity-gain-capable inputs and a powered Naim phono-stage input provide substantial flexibility. A separate power amplifier and loudspeakers are still required, and there is no internal DAC, streamer, phono stage or headphone amplifier.
Naim NAC 552 Preamplifier with 552 PS DR
The NAC 552 is Naim's reference 500 Series preamplifier in the established Classic-format chassis. Its two-box arrangement removes the mains transformer and power-supply circuitry from the enclosure carrying the low-level audio stages.
A fully suspended brass sub-chassis supports the sensitive circuit boards, while precision rotary controls, independent source and recording selection, assignable inputs and remote operation provide the required control over a complex high-performance system.
Designed For
- Reference-level Naim separates systems
- Compatible DIN and RCA analogue source components
- Naim stereo, dual-mono or mono power amplifiers
- Systems requiring separate source and record selection
- Compatible home-cinema integration through unity gain
- Powered Naim StageLine or SuperLine phono-stage installations
- Dedicated two-level equipment support with careful cable dressing
Important Limitations
- The NAC 552 cannot operate without its 552 PS power supply
- The 555 PS DR is not the correct supply for this preamplifier
- A separate power amplifier and loudspeakers are required
- No digital inputs, DAC or network streaming are built in
- No MM or MC phono stage is built in
- No headphone output is provided
- All source and power-amplifier cables must be correctly matched
A Complete Two-Box Package
The package comprises the NAC 552 preamplifier and its dedicated 552 PS DR power supply. Both units measure 87 x 432 x 314mm, so each requires its own full-width equipment-support level.
The NAC 552 weighs 12.9kg and the 552 PS DR weighs 13.9kg, giving a combined equipment weight of 26.8kg before cables. The power supply contains the mains connection and front-panel power switch; the preamplifier itself is powered through the supplied inter-chassis leads.
552 PS DR, Not 555 PS DR
The 552 PS DR is purpose-designed for the NAC 552 and is included in this listing. The 555 PS DR is a different supply used with compatible Naim source components and must not be substituted. The previous reference to adding a 555 PS DR to a “NAC 555” was incorrect.
Discrete-Regulated 552 PS DR
The separate supply uses an 800VA toroidal transformer, three smoothing capacitors and Naim Discrete Regulator technology. Moving this large transformer and its associated electromagnetic field into another enclosure helps protect the preamplifier's low-level audio circuits.
The 552 PS DR provides multiple regulated rails, published as positive and negative 22V, positive and negative 10V, 12V and two 15V supplies. These rails serve different audio and control sections through the dedicated Burndy and SNAIC connections.
Two Essential Inter-Chassis Cables
A NAC 552 Burndy cable and a 5-pin SNAIC connect the preamplifier to the 552 PS DR. Both are required. The SNAIC is directional, with its marked end oriented according to Naim's connection diagram.
Naim recommends routing the Burndy and 5-pin DIN cables close together while allowing them to hang freely without tight bends or pressure from the wall or equipment stand. The complete system must be switched off before either lead is connected or removed.
Power-Amplifier Signal Routed Through the Supply
To maintain the intended system-earth continuity, the NAC 552's variable signal output is routed through the 552 PS DR. Power-amplifier connections are therefore made at the power-supply chassis rather than directly from a conventional preamplifier output on the NAC 552 enclosure.
Multiple DIN output sockets support compatible stereo, dual-mono and separate mono power-amplifier arrangements. The correct output and cable depend on the chosen amplifier, so the complete pairing should be confirmed before installation.
Six Source Selections and Nine Socket Positions
The front panel provides six source-selection buttons: CD, Tuner, Tape, AV, AUX 1 and AUX 2. These can be assigned to the required physical input sockets during setup.
The rear panel provides seven DIN input positions and two RCA input pairs. The RCA sockets are alternative assignable connections within the six-source control architecture rather than two additional front-panel source buttons.
DIN Input Arrangement
- Inputs 1, 2 and 3 are DIN input-only sockets
- Inputs 4, 5 and 6 are DIN input and fixed-level output sockets
- Inputs 4 and 5 can be configured for unity gain
- Input 7 is a DIN input with a DC power output for a compatible Naim phono stage
- Inputs 8 and 9 are stereo RCA pairs
Naim recommends DIN connections where both DIN and RCA options are available and compatible. Socket assignment, cable direction and the electrical function of DIN input and output connections must be checked before use.
Independent Listen and Record Banks
The upper source bank selects the input heard through the main variable output. The lower record bank can independently route a different source to the fixed-level record outputs on the DIN input and output sockets.
This allows one source to be monitored while another is sent to a compatible recorder. When recording outputs are not required, Naim recommends engaging record mute to reduce unnecessary circuit activity and power consumption.
Three Fixed-Level Record Outputs
DIN inputs 4, 5 and 6 also provide fixed-level stereo outputs controlled by the record-selection bank. The published tape-output reference is 75mV with a 600O output impedance.
Avoid connection layouts that return a selected record output to its own input, as this can create a feedback loop. Confirm the pin arrangement of any recorder or external processor before connecting it to a DIN input and output socket.
Two Unity-Gain-Capable Inputs
Inputs 4 and 5 can be configured for unity gain when integrating a compatible AV processor. In this mode, the external processor controls the listening level for that input and the NAC 552 volume control is bypassed.
Unity gain can produce very high output if the connected processor is not configured correctly. Audio T should set up or verify the complete home-cinema signal path before the mode is enabled.
Powered External Phono-Stage Input
Input 7 includes a DC supply for a compatible Naim StageLine or SuperLine phono preamplifier. The turntable still requires the correct external phono stage because the NAC 552 does not contain cartridge amplification or RIAA equalisation.
Cartridge type, phono-stage version, loading, input cable and powered DIN connection must all be matched. Do not connect equipment that is not designed to receive power from this socket.
Suspended Brass Sub-Chassis
The NAC 552's sensitive audio circuit boards are mounted to a brass sub-chassis suspended on coil springs. This construction is intended to reduce mechanical vibration reaching the low-level circuitry.
Correct levelling and support remain important because the suspension is designed to operate within a properly installed chassis. The unit should not be stacked directly on another component or placed on an unstable surface.
Volume, Balance, Mono and Mute Controls
Precision rotary potentiometers with precious-metal wipers control volume and channel balance. Front-panel mono and mute functions support setup, listening checks and safe source changes.
Naim publishes 29dB of analogue gain, with the maximum-volume reference at 22dB. The main output reference is 0.775V with an output impedance below 50O and a minimum connected load of 10kO.
Remote and RC5 Control
The supplied Naim remote handset operates source selection, record selection, volume, balance, mute and other supported functions. A rear-panel RC5 input allows compatible wired remote-control or system-integration commands.
The NAC 552 does not include network control or audio streaming. The RC5 socket is a control connection rather than an audio input.
Analogue Preamplifier Only
All programme inputs are analogue. A network player, CD transport or television must provide a compatible analogue output, either from its own internal DAC or through a separate digital-to-analogue converter.
There is no USB audio, Bluetooth, HDMI, optical digital input, coaxial digital input or headphone socket. These functions must be provided by other components where required.
Power Modes
Current Naim specifications state 15W consumption in normal use, below 2W in network standby and below 0.5W in low-power standby. Automatic standby can be enabled or disabled, with a selectable two-hour inactivity period.
Only the 552 PS DR connects to mains power. Source components and power supplies should be switched on before the power amplifier, with the process reversed when shutting down for connection changes.
Equipment Support and Placement
Both enclosures need stable, separate equipment-support levels. Keep the power supply and power amplifiers a reasonable distance from the preamplifier and source components to reduce the possibility of hum and magnetic interference.
Position both boxes before connecting the Burndy and SNAIC. The rack must support at least 26.8kg for the package alone, plus the weight of any other equipment, shelves and cables.
Supplied Accessories
The package includes the NAC 552, 552 PS DR, Naim remote handset, batteries, NAC 552 Burndy cable, directional 5-pin SNAIC and PowerLine mains cable. Source interconnects and power-amplifier connection cables depend on the selected system.
Key Features
- Complete NAC 552 and 552 PS DR two-box preamplifier system
- Dedicated 800VA discrete-regulated power supply
- Fully suspended brass sub-chassis
- Six assignable source-selection controls
- Seven DIN input positions and two RCA input pairs
- Independent source and record-selection banks
- Three fixed-level DIN record outputs
- Two unity-gain-capable inputs
- Powered DIN input for compatible Naim phono stages
- Multiple DIN power-amplifier output connections on the 552 PS DR
- Remote handset and RC5 control input
- Burndy, SNAIC and PowerLine cables supplied
Frequently Asked Questions
Does this listing include the power supply?
Yes. It includes both the NAC 552 preamplifier and the dedicated 552 PS DR required to power it, together with the Burndy, SNAIC and mains cables specified for the package.
Can the NAC 552 use a 555 PS DR?
No. The correct supply is the 552 PS DR. The 555 PS DR is intended for compatible Naim source components and is not a NAC 552 power supply.
Does the system drive loudspeakers directly?
No. A compatible power amplifier is required between the 552 PS DR signal output and the loudspeakers.
Why are there nine input sockets but six source buttons?
The rear panel provides seven DIN positions and two RCA pairs. The six source buttons can be assigned to the required sockets, so the system supports six directly selected source functions at one time.
Can I listen to one source while recording another?
Yes. The source and record banks operate independently, allowing one source to feed the main variable output while another is routed to the fixed-level record outputs.
Does it include a phono stage?
No. Input 7 can power a compatible Naim StageLine or SuperLine, but cartridge amplification and equalisation take place in that external phono stage.
Does it include a headphone socket?
No. Headphone listening requires a separate headphone amplifier connected through a suitable fixed or variable signal path.
Can it accept a digital source?
Only through the source's compatible analogue output or a separate DAC. The NAC 552 has no optical, coaxial, USB or HDMI audio inputs.
Where does the power amplifier connect?
The variable audio signal is routed through the 552 PS DR. Compatible power-amplifier cables therefore connect to the appropriate DIN output socket on the power supply.
Can the two boxes be stacked?
No. Each enclosure should have its own stable equipment-support level, with the power supply positioned away from the sensitive preamplifier and source components where practical.
Why Buy From Audio T?
The NAC 552 system uses specialised power, signal, powered-phono and record-output connections. Audio T can confirm every source assignment, cable type, unity-gain setting and power-amplifier connection before installation.
Your local store can also demonstrate the complete preamplifier and 552 PS DR combination, plan suitable Fraim support, dress the Burndy and SNAIC correctly, and integrate compatible source, phono and power-amplifier components.
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