Audio T Verdict
The Audio Note I Zero is a compact valve integrated amplifier for systems that value straightforward operation over an extensive feature list.
Four ECL82 triode-pentode valves produce 8 watts per channel in Class A/B, with Audio Note's own custom-designed output transformers connecting the valve output stage to the loudspeakers.
Four line-level inputs provide useful source flexibility, but there is no built-in phono stage, DAC, streaming or headphone output. Its modest power also makes careful loudspeaker matching essential.
Audio Note I Zero ECL82 Valve Integrated Amplifier
The Audio Note I Zero combines source selection, volume control and stereo valve power amplification in one compact chassis.
It uses four ECL82 triode-pentode valves operating in Class A/B to produce 8 watts RMS per channel into a specified 6O loudspeaker load.
Four line-level inputs allow conventional analogue source components to be connected without requiring a separate preamplifier.
A Line-Level Integrated Amplifier
The I Zero accepts analogue line-level sources. It does not include a phono stage, digital-to-analogue converter, network streamer, Bluetooth receiver or headphone amplifier.
A turntable requires a suitable external phono stage, while a digital transport, television or computer requires an appropriate DAC.
What Is an Integrated Amplifier?
An integrated amplifier combines a preamplifier and power amplifier in one unit.
The I Zero's input selector chooses between connected sources, while its volume control sets the listening level. The internal power-amplifier section then drives a pair of passive loudspeakers.
No separate line preamplifier or stereo power amplifier is required for normal use.
Typical Signal Path
- Analogue source component
- I Zero line-level input
- Input selector and volume control
- ECL82 valve amplifier stage
- Audio Note output transformers
- Passive loudspeakers
Additional Equipment Required For
- Turntables without a phono stage
- CD transports without analogue outputs
- Computers and televisions
- Network music streaming
- Bluetooth playback
- Headphone listening
Four Analogue Line Inputs
The I Zero provides four line-level inputs for source components with conventional analogue outputs.
Suitable sources include CD players, external DACs, network streamers, tuners and phono stages.
The inputs do not apply phono equalisation or provide the additional gain required by a turntable cartridge. A turntable must connect through a compatible phono stage unless the turntable already includes one.
Simple Manual Controls
Operation is centred on an input selector and volume control.
There are no display menus, digital filters, network settings or software applications to configure.
Audio Note does not publish remote-control operation for the I Zero, so it should be treated as a manually controlled amplifier.
Four ECL82 Triode-Pentode Valves
The amplifier uses four ECL82 valves, with two valves serving each stereo channel.
An ECL82 combines a small-signal triode and an output pentode in the same glass envelope. This allows the voltage-amplification, driver and output functions to be achieved with a relatively compact valve complement.
The four-valve arrangement contributes to the I Zero's smaller chassis and comparatively low 75W maximum power consumption.
Class A/B Operation
Audio Note specifies the I Zero as a Class A/B amplifier.
This differs from the pure Class A single-ended operation used by a number of Audio Note's larger amplifiers.
Class A/B allows the I Zero to produce its rated output from a compact circuit while using considerably less power than Audio Note's larger pure Class A designs.
This Is Not a Single-Ended Class A Amplifier
The I Zero uses four ECL82 valves in a Class A/B configuration. It should not be described as a pure Class A, single-ended or directly heated triode amplifier.
Its operating circuit is distinct from Audio Note amplifiers based on 300B or 211 output valves.
8 Watts per Channel
The I Zero produces a rated 8 watts RMS per channel into a 6O loudspeaker load.
Eight watts can provide satisfying listening levels with appropriately selected loudspeakers, but it is modest compared with most transistor amplifiers.
The speaker's sensitivity, impedance behaviour, listening distance, room size and required volume should all be considered before purchase.
Specified for a 6O Load
Audio Note publishes the I Zero's rated power into a 6O load.
The current specification does not list separate user-selectable 4O and 8O output taps. Loudspeaker compatibility should therefore be assessed from the complete impedance characteristic rather than nominal impedance alone.
Audio T can help determine whether the intended loudspeakers provide a suitable electrical and practical match.
Custom Audio Note Output Transformers
The I Zero uses output transformers designed and manufactured by Audio Note in the UK.
An output transformer provides the electrical interface between the high-impedance valve output stage and the much lower impedance of the connected loudspeaker.
Transformer design is therefore a fundamental part of the amplifier circuit rather than an accessory added after the valve stage.
100kO Input Impedance
The amplifier's line-level inputs have a published impedance of 100kO.
This presents a relatively light load to most conventional CD players, DACs, streamers and phono stages.
Source compatibility should still be checked when using equipment with an unusually high output impedance or very long interconnects.
400mV Input Sensitivity
Audio Note specifies an input sensitivity of 400mV for full amplifier output.
Most conventional line-level sources can provide more than this voltage, so the amplifier should reach full output without requiring an additional preamplifier.
High-output sources may provide a relatively rapid increase in volume over the first part of the control's travel. This does not increase the amplifier's maximum 8-watt output.
Connecting a CD Player
A CD player with stereo analogue outputs can connect directly to any of the I Zero's line inputs.
The compact
Audio Note CD Zero
provides a visually and operationally complementary source.
A CD transport without analogue outputs requires a separate DAC before it can connect to the amplifier.
Connecting a Digital Source
The I Zero does not include digital inputs.
A computer, television, digital transport or digital-only streamer must first connect to a separate digital-to-analogue converter.
The analogue outputs from a DAC such as the
Audio Note DAC 0.1x
can then connect to one of the amplifier's four line inputs.
Connecting a Turntable
The I Zero does not include a moving-magnet or moving-coil phono stage.
A turntable must connect through an external phono stage matched to the fitted cartridge. The phono stage's line-level output can then connect to any available I Zero input.
A low-output moving-coil cartridge may also require a compatible step-up transformer or active moving-coil stage.
Loudspeaker Matching
Efficient loudspeakers with a stable, amplifier-friendly impedance generally provide the most suitable match.
Sensitivity figures offer a useful starting point, but they do not show the speaker's minimum impedance, phase behaviour or the effect of listening distance and room size.
Compact Audio Note loudspeakers such as the
Audio Note AN-K/LX
may be considered as part of a matched system, subject to room and listening requirements.
Good Starting Points
- Efficient passive loudspeakers
- Stable impedance behaviour
- Small or medium-sized rooms
- Moderate listening distances
- Realistic listening levels
- An audition with the intended speakers
Check Carefully When Using
- Low-sensitivity loudspeakers
- Speakers with difficult impedance curves
- Very large listening rooms
- Long listening distances
- High continuous playback levels
- Music requiring substantial bass output
Clipping and Available Power
When an amplifier is asked to produce more power than it can supply, the output waveform begins to clip.
Persistent clipping can sound hard or compressed and may place loudspeaker drive units at risk.
If the I Zero cannot provide the required listening level without audible strain, a more efficient loudspeaker or a more powerful amplifier should be considered.
Compact Zero-Series Chassis
Audio Note's current specification gives dimensions of 96mm high, 300mm wide and 310mm deep.
This makes the I Zero considerably narrower than conventional full-width hi-fi equipment while still allowing room for four valves and two custom output transformers.
The amplifier weighs 7kg and should be placed on a stable, level and heat-resistant support.
Current Published Dimensions
The current Audio Note specification states 96mm high x 300mm wide x 310mm deep.
Allow additional rear space for mains, source and loudspeaker cables, and do not select furniture based on the chassis dimensions alone.
Ventilation and Heat
The internal ECL82 valves produce heat during normal operation.
Allow air to circulate around the chassis and do not install the amplifier inside a tightly enclosed cabinet.
Avoid placing another component directly on top of the I Zero or positioning it immediately above equipment that produces substantial heat.
The amplifier should be allowed to cool before it is moved or serviced.
75W Maximum Power Consumption
Audio Note specifies maximum power consumption at 75W.
The amplifier is manufactured for 100–120V or 220–240V AC operation at 50Hz or 60Hz, according to market.
The correct operating voltage must be confirmed when ordering and before the amplifier is connected to the mains.
Safe System Operation
Connect the source components and loudspeakers before switching on the amplifier.
Source equipment should normally be switched on before the I Zero. When shutting the system down, switch off the amplifier before the source components.
This sequence helps prevent switching noise from connected equipment reaching the loudspeakers at amplifier level.
Valve-Amplifier Safety
- Connect suitable loudspeakers before switching on the amplifier.
- Do not operate the amplifier without a loudspeaker load.
- Allow unobstructed ventilation around the chassis.
- Keep the amplifier away from children and pets.
- Disconnect the mains and allow the unit to cool before moving it.
- Never remove the amplifier cover.
- Internal voltages may remain dangerous after switch-off.
- Servicing must only be undertaken by suitably qualified personnel.
Valve Replacement
Valves have a finite working life and will eventually require testing or replacement.
The four ECL82 valves operate together as part of the stereo amplifier circuit. Suitable replacements should be selected and fitted in accordance with Audio Note's servicing guidance.
Internal access and valve replacement should be left to Audio T or another suitably qualified service technician.
Three Fascia Finishes
The I Zero is available with anodised aluminium, black acrylic or white acrylic fascia finishes.
The Audio T product options currently identify these as aluminium, black and white versions.
The internal valve circuit and output specification remain the same, so the choice is primarily visual. Current availability should be confirmed when ordering.
Key Features
- Compact stereo valve integrated amplifier
- Four analogue line-level inputs
- Manual input selection and volume control
- 8 watts RMS per channel
- Rated into a 6O loudspeaker load
- Class A/B operation
- Four ECL82 triode-pentode valves
- Two ECL82 valves per channel
- Custom Audio Note output transformers
- 100kO input impedance
- 400mV input sensitivity for full output
- Specified channel balance of ±0.3dB
- 75W maximum power consumption
- Compact 300mm-wide chassis
- 7kg unit weight
- Anodised aluminium, black acrylic or white acrylic fascia
Frequently Asked Questions
Is the I Zero a valve amplifier?
Yes. It uses four ECL82 triode-pentode valves, with two valves serving each stereo channel.
Is it a pure Class A amplifier?
No. Audio Note specifies the I Zero as operating in Class A/B.
Is it a single-ended amplifier?
No. It should not be confused with Audio Note's single-ended 300B or 211 amplifiers.
How many inputs does it have?
It provides four analogue line-level inputs for suitable source components.
Does it have a phono stage?
No. A turntable requires a separate phono stage matched to the fitted cartridge.
Does it have digital inputs?
No. Digital sources require a separate DAC with analogue outputs.
Does it include streaming or Bluetooth?
No. A separate streamer or Bluetooth receiver with analogue output is required.
Does it have a headphone socket?
No. A separate headphone amplifier is required for headphone listening.
Does it have remote control?
Audio Note does not publish remote-control operation for the I Zero. Input selection and volume should be treated as manually controlled.
Will 8 watts drive any loudspeaker?
No. Loudspeaker sensitivity, impedance behaviour, room size, listening distance and required volume must all be considered.
Is it suitable for 4O or 8O speakers?
Audio Note rates the amplifier into a 6O load. Compatibility with a nominally 4O or 8O loudspeaker depends on its complete impedance characteristic and should be checked before purchase.
Can it be operated without loudspeakers?
No. Suitable loudspeakers should be connected before the valve amplifier is switched on.
What are the current dimensions?
Audio Note's current specification states 96mm high x 300mm wide x 310mm deep.
How much does it weigh?
The amplifier weighs 7kg.
What finish options are available?
The fascia is available in anodised aluminium, black acrylic or white acrylic, subject to current production and availability.
Why Buy From Audio T?
- Experienced Audio Note valve-system specialists
- Low-power amplifier and loudspeaker matching advice
- Turntable and external phono-stage guidance
- CD player, streamer and DAC compatibility checks
- Valve care and ventilation advice
- System cabling and installation support
- In-store demonstrations through participating branches
- Ongoing valve servicing and system support
Contact your nearest Audio T store
to discuss loudspeaker compatibility, finish availability and demonstration options.