Audio T Verdict
The Naim NPX 300 is a dedicated external power-supply upgrade for compatible Naim sources and pre-amplifiers. It removes the partner component's internal mains supply from active use and provides separate Type 3 and Type 4 feeds for its analogue, digital and control circuitry.
Its most direct current partners are the NSC 222 streaming pre-amplifier, NSS 333 streamer and NAC 332 pre-amplifier. The NDX 2 and NAC-N 272 can also be powered in Legacy Mode with the correct separately available adaptor cable, while selected Type 2 products use a different connection arrangement.
One NPX 300 powers one compatible component at a time. References to using multiple NPX 300 units mean installing a separate supply for each compatible source or pre-amplifier in a system, not connecting several supplies to one component. It does not power Naim power amplifiers and is not interchangeable with the NPX TT or 555 PS DR.
Naim NPX 300 External Power Supply
The NPX 300 is Naim's outboard power-supply upgrade for the New Classic 200 and 300 Series generation. A large toroidal transformer, Naim Discrete Regulator technology and separate power connections are housed in a full-width aluminium enclosure that matches the associated components.
Compatible New Classic products already contain internal power supplies and can operate without an NPX 300. Adding the external supply is therefore an optional system upgrade rather than a requirement for basic operation.
Designed For
- Naim NSC 222 streaming pre-amplifier
- Naim NSS 333 high-resolution streamer
- Naim NAC 332 pre-amplifier
- NDX 2 and NAC-N 272 with the correct legacy adaptor cable
- Compatible Type 2 source products with their own Type 2 cable
- Systems requiring one dedicated supply per compatible component
- New Classic systems supported by a suitable equipment rack
Important Limitations
- It does not process or reproduce an audio signal
- It powers one compatible partner product at a time
- It does not power a NAP 250, NAP 350 or other power amplifier
- It cannot power the ND 555 network player
- It is not the NPX TT power supply for the NVC TT phono stage
- Legacy products require a separately available adaptor cable
- Its Micro USB socket is for service updates only
- Its 14.4kg weight requires stable equipment support
Separating the Power Supply from the Audio Component
Mains transformers, rectifiers and charging currents create electrical fields, vibration and switching noise. Moving the main supply into a separate enclosure gives the connected source or pre-amplifier a quieter physical and electrical environment in which to operate.
When an NPX 300 is installed with a compatible New Classic product, the partner's mains lead is removed and its rear-panel link plugs are taken out. The NPX 300 then becomes the only component connected directly to the mains and provides the required DC supplies through the two Burndy cables.
This arrangement bypasses the partner component's internal main supply for normal operation. It does not add a second mains transformer in parallel with the internal supply, and both products must never be left connected to mains during the installation procedure.
Transformer and Discrete Regulator Technology
The NPX 300 uses a purpose-designed transformer and multiple Naim Discrete Regulator stages. The regulator architecture is intended to provide stable, low-noise DC rails while responding quickly to changing current demand from the connected audio, digital and control circuits.
The Type 3 output provides the main positive and negative analogue supply rails together with an accessory feed. The Type 4 output provides separate positive-voltage feeds for digital and control circuitry, including the low-power standby function and communications with compatible New Classic products.
These are dedicated product connections rather than user-adjustable DC outputs. Voltage rails, connector pin assignments and cable types must never be adapted for unapproved Naim or third-party equipment.
Type 3 and Type 4 Burndy Cables Included
One Type 3 and one Type 4 Naim power-supply cable are supplied with the NPX 300. Compatible 200 and 300 Series products use both cables: the Type 3 and Type 4 outputs are not two independent sockets for powering two separate components.
The cable ends marked with one or two direction bands connect to the source or pre-amplifier. The unmarked ends connect to the NPX 300. Each cable must be routed to its matching socket without twisting the plug body or forcing the pins.
One Supply Per Partner Component
A single NPX 300 uses both supplied Burndy cables to power one NSC 222, NSS 333 or NAC 332. If a system contains both an NSS 333 and NAC 332, two NPX 300 units may be used so that each component has its own external supply.
Do not attempt to use the Type 3 output for one product and the Type 4 output for another. The two feeds form one coordinated supply system for a single compatible partner.
NSC 222 Streaming Pre-Amplifier
The NSC 222 was the first direct partner for the NPX 300. It can operate from its own internal supply, but the external upgrade removes its mains lead and two rear link plugs before both supplied NPX 300 cables are connected.
Standby operation and logo brightness can be synchronised between the two units. The NPX 300 supplies the NSC 222 only; the partnering NAP 250 or other power amplifier retains its own mains connection.
NSS 333 Streamer
The NSS 333 is the dedicated 300 Series streaming source and accepts the NPX 300 through its Type 3 and Type 4 upgrade sockets. As with the NSC 222, the streamer operates independently from its internal supply until the external upgrade is installed.
After installation, only the NPX 300 connects to mains for this source pairing. The NSS 333's link plugs and original mains cable should be stored safely so the streamer can be returned to standard internal-power operation if required later.
NAC 332 Pre-Amplifier
The NAC 332 also supports an NPX 300 through separate Type 3 and Type 4 connections for its analogue and control sections. The procedure again requires the pre-amplifier to be switched off, disconnected from mains and fitted with both supplied power cables after its link plugs are removed.
An NPX 300 connected to the NAC 332 does not power the NVC TT phono stage directly or provide mains power to NAP 350 mono amplifiers. Those products retain their own specified supply arrangements.
NDX 2 and NAC-N 272 Legacy Mode
Naim's current NPX 300 product information specifically names the NDX 2 and NAC-N 272 as compatible when the correct special cable is used. The standard Type 3 and Type 4 cables supplied for New Classic products are not the complete legacy connection solution.
In Legacy Mode the NPX 300 standby button switches the connected product fully off. Network standby and logo-brightness synchronisation are not supported, so operation differs from a direct New Classic connection.
Some additional Naim sources share historical XPS compatibility, but that does not make every XPS-compatible product automatically approved for the NPX 300. Confirm the exact model, serial number and adaptor cable with Audio T before ordering for any legacy component.
Type 2 and Solstice NVS TT Compatibility
The NPX 300 can power a compatible Type 2 source such as the Naim Solstice Series NVS TT turntable. In that arrangement, the Type 2 cable originally supplied with the turntable connects to the NPX 300's Type 2 or Type 3 output socket.
The Type 2 cable is not listed as an NPX 300 accessory because it belongs to the partner product. The second Type 4 output is not used merely because it is present; the exact connection must follow the Type 2 product instructions.
Not the Same as NPX TT
NPX 300 and NPX TT are different products. The NPX TT is the compact supply associated with the NVC TT phono stage and Solstice platform, while the full-width NPX 300 provides a broader set of Type 3 and Type 4 supply rails for compatible New Classic sources and pre-amplifiers.
Similar model names do not make their outputs, cables or supported products interchangeable. The correct power supply should always be selected by partner product rather than by connector appearance.
Not a Power Supply for the ND 555
The ND 555 network player requires at least one Naim 555 PS DR and cannot be powered by the NPX 300. Its power architecture, required voltage rails and Burndy connections are different.
The NDX 2 is a different design and is specifically supported by the NPX 300 with the correct legacy adaptor. The similarity of the NDX 2 and ND 555 as network players should not be used to infer power-supply compatibility.
Power-Line Lite Included
Naim's current product page and user guide list one Power-Line Lite mains cable with the NPX 300. This corrects older or abbreviated descriptions that refer simply to a Power-Line mains lead without identifying the supplied Lite version.
Use only a unit configured for the local mains voltage. Published versions are for 115V or 230V at 50/60Hz; the voltage should not be assumed to be user-switchable.
Standby, Logo and Control Synchronisation
With compatible 200 and 300 Series products, the front standby control performs the corresponding standby function on the connected component. Low-power standby below 0.5W and network standby are supported, and the NPX 300 logo brightness follows the partner product.
A rear brightness and reset button provides local control where appropriate. Short presses cycle logo brightness in Legacy Mode, while holding it for around three seconds performs a factory reset. It should therefore not be held accidentally during routine installation.
Micro USB Service Port
The rear Micro USB socket is provided only for service updates. It is not an audio input, storage connection, charging outlet or general computer interface.
Installation and Power Sequence
Place both products in their final rack positions before connecting cables. Switch off the complete system, turn down the pre-amplifier volume and disconnect the relevant mains leads before removing link plugs or fitting a Burndy cable.
For a direct New Classic installation, connect both supplied cables with their direction bands at the source or pre-amplifier, remove that product's mains lead and connect the Power-Line Lite to the NPX 300 only. Source components and supplies should be powered before the power amplifiers.
Never connect or disconnect a power-supply cable while either unit is energised. If a connector does not locate easily, stop and check its type and orientation rather than applying force.
Rack Position, Ventilation and Cable Dressing
At 14.4kg, the NPX 300 requires a level, stable equipment support rated for its weight. Naim recommends a dedicated rack such as Fraim and advises reasonable separation between power supplies, power amplifiers and sensitive audio components to reduce the possibility of hum.
Do not stack another component directly on top or obstruct ventilation. Allow the two Burndy cables to hang naturally without tight bends, contact with the floor or strain at either connector.
New Classic Aluminium Casework
The NPX 300 measures 91.5mm high, 432mm wide and 317.5mm deep including its feet. The full-width aluminium case and illuminated white Naim logo visually match the NSC 222, NSS 333, NAC 332 and associated New Classic amplification.
There are no audio controls, inputs or outputs. The front panel provides standby control, while the rear carries mains, control, service and dedicated power-supply connections.
Key Features
- Dedicated external power-supply upgrade
- Designed for compatible Naim sources and pre-amplifiers
- Direct compatibility with NSC 222, NSS 333 and NAC 332
- NDX 2 and NAC-N 272 Legacy Mode compatibility with special cable
- Supports selected Type 2 products using their own Type 2 cable
- Purpose-designed toroidal transformer
- Naim Discrete Regulator technology
- Separate Type 3 analogue and Type 4 digital or control feeds
- One Type 3 Burndy cable supplied
- One Type 4 Burndy cable supplied
- Power-Line Lite mains cable supplied
- Low-power standby below 0.5W
- Network standby with compatible New Classic products
- Synchronised standby and logo brightness where supported
- Rear brightness and reset control
- Micro USB service-update port
- Full-width aluminium New Classic casework
- Illuminated white Naim logo
Frequently Asked Questions
Which current Naim products can use the NPX 300?
The direct current partners are the NSC 222 streaming pre-amplifier, NSS 333 streamer and NAC 332 pre-amplifier. Each uses both supplied Type 3 and Type 4 cables.
Does a New Classic product need the NPX 300 to work?
No. Compatible NSC 222, NSS 333 and NAC 332 products contain internal power supplies and operate independently. The NPX 300 is an optional performance upgrade.
Can one NPX 300 power two products?
No. Its Type 3 and Type 4 outputs work together to power one compatible product. A system with externally powered NSS 333 and NAC 332 units requires one NPX 300 for each component.
Can two NPX 300 units be connected to one component?
No standard installation uses two NPX 300 supplies on one NSC 222, NSS 333 or NAC 332. References to multiple supplies mean one dedicated NPX 300 for each compatible component in a larger system.
Are the required Burndy cables included?
Yes. One Type 3 and one Type 4 cable are supplied for direct 200 and 300 Series connections. Legacy NDX 2 and NAC-N 272 installations require a different, separately available adaptor cable.
Is a Power-Line supplied?
Naim currently specifies a Power-Line Lite mains cable, not the full Power-Line supplied with certain reference power supplies.
Does the partner product remain connected to mains?
No. For direct New Classic and supported Legacy Mode installations, the partner's mains lead is removed and only the NPX 300 is connected to mains. Follow the exact product instructions before powering the system.
Can it power an NDX 2?
Yes, in Legacy Mode with the correct special Naim adaptor cable. The standard supplied Type 3 and Type 4 leads do not directly replace that adaptor.
Can it power a NAC-N 272?
Yes. Naim lists the NAC-N 272 as compatible with a specific legacy cable. Network standby and logo-brightness synchronisation are unavailable in this configuration.
Can it power the ND 555?
No. The ND 555 requires at least one 555 PS DR. Its power requirements are different from the NPX 300 system.
Can it power the NAP 250 or NAP 350?
No. Those are mains-powered power amplifiers. The NPX 300 is an upgrade for specifically compatible sources and pre-amplifiers, not an external supply for NAP power amplifiers.
Is the NPX 300 the same as the NPX TT?
No. They have different enclosures, output arrangements and intended partner products. The NPX TT is associated with the NVC TT phono stage, while the NPX 300 is the full-width New Classic source and pre-amplifier supply.
Can the Solstice NVS TT use it?
Naim's manual lists the Solstice Series NVS TT as a Type 2 example. It uses the Type 2 cable supplied with the turntable, connected to the NPX 300's Type 2 or Type 3 output.
What is the Micro USB socket for?
It is for service updates only. It cannot receive digital audio, play music from storage or charge a user device.
Can the cables be changed while the system is on?
No. Switch off the complete system and disconnect it from mains before removing link plugs or fitting and removing any power-supply cable.
Is the mains voltage user-switchable?
Do not assume so. Naim publishes separate 115V and 230V market versions. Use only a unit correctly configured and labelled for the local supply.
Why Buy From Audio T?
- Compatibility checks for current and legacy Naim products
- Advice on Type 2, Type 3, Type 4 and legacy cable arrangements
- Clear distinction between NPX 300, NPX TT and 555 PS DR
- Single-supply and multi-component system planning
- Safe link-plug removal and power-sequence guidance
- Equipment-rack and Burndy cable-dressing advice
- Demonstration with NSC 222, NSS 333 or NAC 332 by arrangement
- Part-exchange options on suitable equipment
- Ongoing Naim system and servicing support
Contact your local Audio T store
to confirm the partner product, correct power cable, mains version and installation procedure before ordering.
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