Naim Audio Flat-Cap XS
Overview
At Naim, a component’s power supply has never been a mere accessory. Moving the power supply of a preamplifier or CD player into a separate enclosure is an upgrade the brand has long offered its customers, and the XS series has its own option. This low-profile unit, the same size as the other components in the range, replaces the internal power supply of one or two Naim components and can be installed without changing anything else in the system.
Two isolated power supplies in one enclosure
The term “dual rail” describes a straightforward design. A single mains transformer sits inside the enclosure, but it has two separate secondary windings, each powering its own rail. The two outputs therefore do not share a winding: changes in one component’s power consumption do not affect the other component connected to it. Downstream, four low-noise regulators, individually tested and selected by Naim, stabilize the 24 V outputs. A regulator is the component that maintains a constant voltage regardless of the current being drawn at any given moment.
The expected benefit comes from relocating the power supply. In a CD player or preamplifier, the transformer and its circuits share an enclosure with audio electronics that handle very low-level signals. Moving them into a dedicated, more generously sized enclosure keeps the transformer’s magnetic field and mains interference farther away. Naim expects clearer sound, more pronounced dynamics and a better sense of rhythm—three qualities by which the brand has judged its components since the beginning.
The XS series components it powers
Three XS series components have an input designed for this power supply: the CD5 XS CD player, the NAT05 XS FM tuner and the NAC 152 XS preamplifier. A single FlatCap XS can power two of them at once, one from each output. The pairings Naim proposes are the CD player and tuner in a system with an integrated amplifier, or the CD player and preamplifier in a separates system. The StageLine phono preamplifier, which connects behind the NAC 152 XS, is also compatible.
The NAC 152 XS has a two-stage upgrade path. It can first use one FlatCap XS output, then both outputs of a single unit dedicated entirely to it. In a complete XS system (CD player, tuner, preamplifier and NAP 155 XS power amplifier), Naim allows for a second or even a third FlatCap XS, with each then powering just one component. This upgrade can be made without replacing anything: each added unit is integrated into the existing setup.
The NAIT XS integrated amplifier and NAP 155 XS power amplifier are not on the list. Both rely on a large internal transformer sized for their power stages and have no input for an external power supply. In a system built around the NAIT XS, the FlatCap XS therefore powers the upstream sources.
DIN cable connections, in Naim’s prescribed order
The rear panel has two power outputs, labeled A and B, and four signal sockets. All connections use DIN sockets, Naim’s preferred connector type, and a SNAIC interconnect cable is supplied. The signal sockets serve a particular purpose in Naim systems: when the preamplifier is powered by the FlatCap XS, its output signal passes through the power supply before reaching the power amplifier. The brand advises against modifying the original cables, for both safety and performance reasons.
Powering up follows a consistent Naim rule. Sources and power supplies are switched on before power amplifiers; when switching off, turn off the amplifiers and wait a minute before connecting or disconnecting a cable. A faint thump from the speakers when the power amplifier is switched on is normal and harmless.
The run-in period is long. According to Naim, the sound may continue to evolve for more than a month, and leaving the system powered on for extended periods produces more consistent results. The trade-off is exposure to lightning: during a thunderstorm, it is best to switch everything off and unplug it.
A low-profile enclosure sized to match the XS series
At 432 × 301 × 70 mm, the FlatCap XS has exactly the same width, depth and height as the CD5 XS, NAC 152 XS and NAIT XS. Its black anodized brushed-aluminum front panel and painted cover give it the same appearance as the rest of the range, and it weighs 5.5 kg.
Matching the other components visually does not mean it should be placed directly on top of them. Naim recommends keeping power supplies and power amplifiers a reasonable distance from other components to reduce the risk of hum, with the interconnect cable length setting the limit. A separate shelf in the hi-fi rack is the simplest solution. The transformer may also emit a faint mechanical hum when the mains supply is disturbed by other household appliances. This noise remains in the enclosure and does not come through the speakers; a dedicated electrical circuit for the system generally reduces it.
Documentation
French
Technical specifications
Intended use
- Power supply for Naim Audio players and amplifiers
Outputs
- DC outputs: 2 × 22 V or 2 × 24 V
- Audio outputs: 4 × 24 V
Mains power
- Mains power: 230 V at 50 or 60 Hz
- Mains voltage: 100 / 115 / 230 V
- Frequency: 50–60 Hz
Physical specifications
- Dimensions (W × D × H): 432 × 301 × 70 mm
- Weight: 5.5 kg
- Colour: black
- Finish: anodised front panel, painted cover
Shipping
- Shipping dimensions (W × D × H): 580 × 500 × 200 mm
- Shipping weight: 7.5 kg
Frequently asked questions
Can the ND5 XS network player be powered by the FlatCap XS?
No. The ND5 XS requires different voltages (±22 V), which the FlatCap XS does not provide. Its external power supply options are the XP5 XS and, higher up in the Naim range, the XPS and 555 PS.
One FlatCap XS shared between two devices, or one per device: what’s the difference?
Sharing one unit between two devices already delivers most of the benefit, since each has its own winding and regulators. Naim nevertheless presents adding a second or third unit, each dedicated to a single device, as the next step in upgrading an XS system. For the NAC 152 XS, connecting both outputs of the same FlatCap XS is the most fully developed configuration.
Is it compatible with devices from other brands?
No. The voltages are supplied through specific pins on the DIN connectors, according to Naim’s proprietary pinout. Connecting the FlatCap XS to a device it was not designed for could damage it.
Do I need to change any settings on the preamplifier or CD player once the FlatCap XS is connected?
Depending on the device, a factory-installed link connector at the rear (which connects the internal power supply to the audio circuits) must be removed before connecting the external power supply. The manual for each device describes the connection procedure to follow, and it is best to keep this connector rather than throw it away in case you switch back to the internal power supply.
Which power cable should I use?
Naim recommends using the supplied power cord or its Power-Line mains cable. The brand advises against fuses with a lower rating than specified and interference filters built into power outlets, which it says degrade the quality of the mains supply. A dedicated electrical circuit for the hi-fi system, installed by an electrician, generally improves the performance of the system as a whole.
Can the user adjust the mains voltage?
No. The FlatCap XS is available in 100, 115 and 230 V versions, operating at 50 or 60 Hz, and each unit is configured at the factory for the country where it is sold. Units sold in France are designed for 230 V.
Should DIN connectors be cleaned regularly?
Simple maintenance is enough: switch off the equipment, unplug the connectors, then plug them back in. The friction cleans the contacts. Naim advises against contact cleaners and “enhancers,” whose residual film can degrade sound quality.
- Eco-contribution of €2.58 included in the sale price.
- GTIN / EAN: 5060332102099
