Primare I35 silver

Primare I35: Class D amplification and modularity

Class D has long carried a reputation for clinical, warmth-free sound. Primare has made it the foundation of its entire range of amplifiers, and the I35 delivers 150 watts per channel into 8 ohms in a compact chassis that barely gets warm. Swedish-designed, it combines modern analog amplification, a carefully engineered power supply and an upgradeable approach: start with a fully analog integrated amplifier, then add digital capabilities later if needed.

UFPD 2: Class D according to Primare

The I35 is based on the second generation of Primare’s in-house UFPD (Ultra Fast Power Device) technology, a fully analog Class D amplification design. Class D operates by switching the output transistors extremely rapidly, rather than continuously dissipating energy like Class AB. Efficiency rises to around 90%, heat generation remains low, and large heat sinks become unnecessary. This makes such a slim chassis possible while still delivering high power.

In terms of figures, the I35 provides 150 watts per channel into 8 ohms, and twice that—300 watts—into 4 ohms. This behavior matters: a speaker whose impedance drops in the bass requires more current, and an amplifier that doubles its power as the load decreases maintains control over speakers that are difficult to drive. The UFPD 2 design aims for a linear response across the entire audible range, without added treble coloration.

The power supply matters as much as the amplification stages in achieving this result. Primare uses a switch-mode power supply with active power factor correction (APFC). In practical terms, it draws current from the mains cleanly and evenly, stabilizes the voltage supplied to the amplification section and limits interference fed back to other components in the system. During dynamic passages, it quickly delivers the current required.

An analog integrated amplifier that can evolve

In the black version presented here, the I35 is a purely analog integrated amplifier: two balanced XLR inputs, three unbalanced RCA inputs, plus preamplification and amplification stages. There is no digital circuitry onboard initially. This is a consistent choice for those who already own a high-quality analog source, a turntable with a phono preamp or a separate network player.

What comes next depends on your needs. The chassis accommodates two optional modules that fit inside: the digital-to-analog converter DM36, which adds digital inputs, and the SM35 Prisma network module, which adds streaming playback and app control. They can be installed at the time of purchase or several years later, without replacing the unit. The cost is spread over time, and the I35 follows the evolution of the system instead of being replaced.

The I35 also fits naturally into a cohesive Primare setup. Paired with the CD35 CD and network player or the DD35 transport from the same range, it forms a system in which every component shares the same design philosophy.

Balanced connectivity and system control

The two balanced XLR inputs deserve closer attention. A balanced connection carries the signal over two conductors with opposite phase, cancelling noise picked up along the way. With a long cable between a source and the I35, or in an electrically busy environment, the improvement in cleanliness is noticeable. The three RCA inputs accommodate more conventional sources.

On the output side, the I35 features a fixed-level line output, useful for a recorder or a second zone, as well as a variable-level preamplifier output. The latter enables several uses: driving an active subwoofer, adding an external power amplifier for bi-amping speakers, or using the I35 as a preamplifier in a larger installation.

The rest of the connectivity is geared toward carefully integrated installations. The C25 system remote control operates via infrared. An infrared input and output on 3.5 mm mini-jacks connect the I35 to a centralized control system or allow it to be housed in a closed cabinet. A 12-volt trigger output on a mini-jack automatically powers on a connected device, such as a power amplifier, when the unit is switched on. The RS232 port enables control through a home automation system.

Compact format and Swedish signature

Eleven kilograms, 430 millimeters wide, 106 high and 420 deep: the I35 fits into most hi-fi furniture without requiring the height of a comparably powerful Class AB amplifier. This modest weight is due to the absence of a large linear transformer and bulky heat sinks, a direct consequence of Class D operation and the switch-mode power supply.

The black finish follows the Scandinavian design principles dear to Primare: understated lines, a clean front panel, and controls reduced to the essentials. The central rotary knob, a visual hallmark of the brand, adjusts volume and selects the source with a precise operating feel. This approach can be summed up in a Swedish word that Primare readily uses, “lagom”: the idea of the right balance, neither too much nor too little.

Frequently asked questions

Can the I35 accept a turntable directly?

No, the analog version does not include a phono preamp. A turntable must go through an external phono preamplifier (such as Primare’s R35) or through a turntable with a built-in preamp before connecting to one of the I35’s line inputs.

Is there a headphone output?

The I35 does not offer one. For headphone listening, connect a headphone amplifier to the line output or preamplifier output.

Does the black version play high-resolution files?

Not as it stands: without a converter, it only handles analog signals. To play digital files, including high-resolution formats, you need to add the DM36 DAC module, connect an external converter, or install the SM35 Prisma network module.

Can the DM36 and SM35 modules be easily added after purchase?

They are installed inside the chassis and connect to the main board. The operation requires opening the unit, so it is best entrusted to a Primare installer, who will also check the internal software update. Once installed, the modules are recognized by the I35 without any further action.

Is the I35 suitable for low-sensitivity speakers or a large room?

Its 300 watts into 4 ohms and its ability to deliver current allow it to handle demanding speakers and high listening levels. In a large room or with power-hungry floorstanding speakers, it retains plenty of headroom. The right match always depends on speaker sensitivity and the area to be covered; when in doubt, a real-world audition remains the best answer.

What finishes are available for the I35?

Two: the black version presented here and a light gray titanium version. Both share the same chassis and electronics.

What is its power consumption?

Around 0.5 watts in standby and approximately 42 watts in normal operation, with actual consumption increasing with volume. Class D efficiency and active power factor correction keep power demand moderate for an amplifier of this output.

Technical Specifications

Amplification

• Output power:
  • 2 × 150 W at 8 Ω
  • 2 × 300 W at 4 Ω
• Class D amplifier
• Amplification module: Primare UFPD 2
• Power supply: Primare APFC

Connectivity

• Analog inputs: 2 XLR, 3 RCA
• Analog outputs: 1 RCA line, 1 RCA preamp
• Control:
  • C25 infrared (IR) system remote control
  • Infrared input/output on 3.5 mm mini-jack
  • 12 V trigger output on 3.5 mm mini-jack
  • External RS232 system control port

Physical Characteristics

• Dimensions (W × D × H): 430 × 420 × 106 mm
• Weight: 11 kg