Audio T Verdict
The Naim 555 PS DR is the company's reference external power supply for compatible digital source components. Its large transformer, seven regulated supply rails and Discrete Regulator technology are designed to provide stable, low-noise DC power while moving a substantial transformer away from sensitive source circuitry.
It is required for the ND 555 network player and can upgrade a range of current and legacy Naim sources, but compatibility is product-specific. The correct Burndy cable, output socket arrangement, link plug and power sequence must be confirmed for the component being connected.
A Naim Power-Line mains cable is supplied. The 555 PS DR is not a music player, power amplifier, universal power conditioner or power supply for arbitrary third-party equipment.
Naim 555 PS DR Power Supply with Power-Line
Also identified on Naim's current website as the NAPS 555 DR, the 555 PS DR is a dedicated outboard power supply for compatible Naim source components.
Its purpose is to provide the connected source with multiple regulated DC supply voltages from a separate, mechanically isolated enclosure. This reduces the need for sensitive audio and digital circuits to share a case with a large mains transformer and rectification circuitry.
Designed For
- Mandatory external power for the Naim ND 555
- Power-supply upgrades for compatible Naim source components
- NDX 2 and selected current Naim streaming products
- Compatible legacy streamers, CD players, servers and DACs
- Systems where the correct Naim Burndy connection is available
- Reference Naim systems supported by a suitable equipment rack
Important Limitations
- It does not play music or contain a DAC
- It does not power Naim power amplifiers or passive pre-amplifiers
- It is not a mains distribution block or universal conditioner
- Burndy cable requirements vary between partner products
- Not every compatible source uses both output sockets
- Legacy compatibility should be checked by model and serial number
- Its 15.7kg weight requires suitable support
Why an External Power Supply?
Audio and digital circuits depend on clean, stable supply voltages. Changes in current demand, transformer vibration, rectifier switching and electromagnetic fields can all affect the environment in which sensitive source circuitry operates.
The 555 PS DR places its transformer, rectification and regulation in a separate full-width enclosure. It then sends the required DC supplies to the compatible source through one or two multi-pin Naim power connections, depending on the product.
This is a system-specific engineering upgrade. It should not be described as a generic improvement for every Naim component or as a device that filters the mains supply for other products. Selected powered streaming pre-amplifiers may be compatible, but conventional passive Naim pre-amplifiers and power amplifiers use different supply arrangements.
Naim Discrete Regulator Technology
DR denotes Naim's Discrete Regulator design. Rather than relying on a standard three-terminal monolithic regulator, Naim uses a regulator assembled from selected discrete components and developed for low noise, rapid recovery from changing current demands and stable operation with both positive and negative supply rails.
The design incorporates a low-noise voltage reference, constant-current source, filtering, an amplifier stage, series power transistor and protection circuitry. Naim also revised transformer mounting, wire gauge, cable routing, mechanical decoupling, internal layout and reservoir capacitors when introducing the DR configuration.
DR and Earlier 555 PS Models
This listing is for the factory DR version. Earlier 555 PS units without the DR designation are not identical internally, so the terms 555 PS and 555 PS DR should not automatically be treated as interchangeable when comparing used products.
Large Transformer and Seven Regulated Supplies
Naim specifies a transformer 40 per cent larger than the one fitted to the XPS. Five separate secondary windings feed seven regulated supply voltages, including a dedicated supply originally provided for the CD555 clock circuitry.
The published DC rails are positive and negative 22V, positive and negative 10V, one 12V supply and two 15V supplies. These are delivered through Naim's dedicated multi-pin power connections rather than conventional user-accessible DC sockets.
The low-resonance case and isolating feet are intended to control mechanical energy as well as contain the substantial transformer and power-supply circuitry.
Two Power-Output Sockets
The rear panel provides two multi-pin power-output sockets. They allow separate supply arrangements for products designed to use distinct analogue and digital feeds, while many compatible legacy sources use Output 1 only.
Do not assume that both sockets should always be connected. The required output, Burndy cable type and any source-side blanking or link plug depend on the partner component and must follow its own manual.
The Correct Burndy Connection Is Essential
Naim Burndy leads are product-specific multi-pin power cables. Similar external appearance does not make different Burndy types electrically interchangeable.
The 555 PS DR is listed as supplied with a Power-Line mains cable; a universal Burndy cable is not listed as a supplied accessory. Some compatible source products include their required connection cables. Confirm the complete cable set before ordering the power supply on its own.
ND 555 Network Player
The Naim ND 555 has no conventional internal mains power supply and must be used with at least one 555 PS DR. One power supply provides the required feeds for normal operation.
Naim also supports using two 555 PS DR units with the ND 555, separating its principal supply sections between two enclosures. The second supply is an optional system upgrade rather than a requirement for basic operation.
The required ND 555 Burndy connections should be installed exactly as shown in the network player's instructions. A 555 PS DR cannot be replaced by an XPS DR for this application.
NDX 2 and Current Streaming Compatibility
The NDX 2 contains its own internal power supply and can operate by itself. Adding a 555 PS DR is therefore an optional source upgrade rather than an operating requirement.
Naim's current streaming compatibility information also lists the NSS 333 as capable of using a NAPS 555 DR. Connection hardware and installation differ between Classic and New Classic products, so the exact cable or adaptor arrangement should be confirmed before purchase.
The ND5 XS 2 does not provide the same external power-supply upgrade path. It should not be confused with the earlier ND5 XS named in historical power-supply documentation.
Compatible Legacy Naim Sources
Naim's current 555 PS DR product page names the ND 555, NDS, NDX, NDX 2, HDX, DAC and CDX2 among compatible partners. Historical Naim power-supply instructions also cover the CD555, CDS3 and original ND5 XS.
The legacy NAC-N 272 streaming pre-amplifier can also use a 555 PS DR with the correct connection arrangement. Several compatible products are discontinued and may exist in different revisions, so the required output socket, Burndy lead and treatment of any link plug should be checked against the exact product and serial number.
The 555 PS DR was originally developed for the CD555. Other compatible products may use only part of its available supply architecture, but must still be connected only through the arrangement specified by Naim.
Power-Line Mains Cable Included
A Naim Power-Line mains cable is supplied as standard. The cable connects the 555 PS DR to a suitable earthed mains outlet; it is separate from the Burndy lead that carries regulated DC power to the source component.
Use the factory voltage version intended for the local mains supply. The voltage rating must not be assumed to be user-switchable simply because Naim publishes 100V, 115V and 230V market versions.
Installation and Power Sequence
Install the 555 PS DR in its final rack position before making connections. Switch off the complete system, disconnect it from the mains and turn down the pre-amplifier volume before fitting or removing a Burndy cable.
Align each multi-pin plug carefully and secure its locking ring without forcing or rotating the plug body against the pins. Keep the cable naturally dressed and free from strain. Follow the partner product's manual for link-plug removal, mains connection and switch-on order because the procedure is not identical for every source.
Never connect or disconnect a Burndy lead while either unit is powered. If the cable does not locate easily, stop and have the connector orientation checked rather than applying force.
Rack Position and Ventilation
The power supply weighs 15.7kg and should sit on a stable, level equipment support rated for the load. Lift it with care and avoid stacking another component directly on top.
Allow ventilation around the case and keep the transformer-containing power supply sensibly separated from low-level signal cables and sensitive source or pre-amplifier components where the rack layout permits.
The isolating feet form part of the mechanical design. All feet should contact the support evenly and should not be obstructed by loose cables or an undersized shelf.
Brushed Black Anodised Casework
The full-width case measures 87mm high, 432mm wide and 314mm deep. Its brushed black anodised finish matches Naim Classic and 500 Series components.
The front panel carries the power control and status illumination. Source selection, playback and audio settings remain on the connected source; the power supply has no audio controls or network functions of its own.
Key Features
- Reference external power supply for compatible Naim source components
- Known as both 555 PS DR and NAPS 555 DR
- Naim Discrete Regulator technology
- Five transformer secondary windings
- Seven regulated DC supply voltages
- Transformer specified as 40 per cent larger than the XPS transformer
- Two multi-pin power-output sockets
- Separate supply architecture for compatible analogue and digital source sections
- Low-resonance case with isolating feet
- Required for operation of the Naim ND 555
- Supports an optional two-supply ND 555 configuration
- Optional power-supply upgrade for the NDX 2
- Compatible with selected current and legacy Naim source products
- Naim Power-Line mains cable supplied
- Full-width brushed black anodised casework
Frequently Asked Questions
What does the 555 PS DR actually do?
It supplies stable, regulated DC power to a compatible Naim source component and places its large transformer and rectification circuitry in a separate enclosure. It does not process the audio signal itself.
Is NAPS 555 DR the same product as 555 PS DR?
Yes. Naim's current website uses NAPS 555 DR as the page title while its product copy and established model naming also use 555 PS DR.
Is a Power-Line mains cable included?
Yes. Naim lists the Power-Line as a supplied accessory with the 555 PS DR.
Is a Burndy cable included?
Naim lists the Power-Line with the power supply but does not list a universal Burndy cable. The required Burndy type depends on the source, and some source products are supplied with their own connection cables. Confirm the complete cable set before ordering.
Can the ND 555 operate without a 555 PS DR?
No. The ND 555 requires at least one 555 PS DR. Naim also supports adding a second supply as an optional upgrade.
Can it upgrade an NDX 2?
Yes. The NDX 2 operates from its internal power supply but supports the 555 PS DR as an optional external upgrade. The correct connection and source-side setup must be followed.
Can it be used with the NSS 333?
Naim's current streaming compatibility guide lists the NSS 333 as compatible with the NAPS 555 DR. Confirm the required New Classic connection hardware with Audio T before ordering.
Will it power the ND5 XS 2?
No. Historical documentation refers to the original ND5 XS, not the later ND5 XS 2. The ND5 XS 2 has no equivalent external power-supply upgrade connection.
Do all compatible products use both rear output sockets?
No. Many compatible products use Output 1 only, while products with separately powered sections may use both. Follow the manual for the exact source rather than connecting both by assumption.
Can it power a Naim power amplifier or a third-party product?
No. It is intended for specifically compatible Naim source components and selected powered streaming pre-amplifiers. It cannot power a Naim power amplifier and should never be adapted for unrelated equipment.
Can Burndy cables be changed while the system is switched on?
No. Switch off and disconnect the relevant equipment from the mains before fitting or removing a Burndy lead. Follow the source manual for the correct connection and power sequence.
Is the mains voltage user-switchable?
Do not assume so. Naim publishes different 100V, 115V and 230V market versions. Use only a unit correctly configured and labelled for the local supply.
Does it require a specialist equipment rack?
A stable hi-fi rack with a shelf rated for at least the 15.7kg product weight is strongly recommended. Adequate ventilation and careful cable dressing are also important.
Why Buy From Audio T?
- Compatibility checks for current and legacy Naim sources
- Advice on the correct Burndy cable and link-plug arrangement
- ND 555 single-supply and twin-supply system planning
- NDX 2 and NSS 333 upgrade demonstrations
- Equipment-rack and cable-dressing guidance
- Safe installation and power-sequence advice
- Part-exchange options on suitable equipment
- Ongoing Naim system and servicing support
Contact your local Audio T store
to confirm source compatibility, serial-number considerations, required connection cables and installation before ordering.
More Details - Register your Naim Product Today