Audio T Verdict
The Rega Osiris is a reference integrated amplifier built for customers who want substantial power, exceptional current delivery and a deliberately minimal analogue signal path.
Its dual-mono construction delivers 162W per channel into 8 ohms and up to 250W per channel into 4 ohms. A passive pre-amplifier section, transformer-balanced XLR input, four RCA line inputs and single power-amplifier stage keep the journey between source and loudspeakers unusually direct.
The Osiris does not include a phono stage, DAC, network streamer or headphone output. At this level, Rega expects each source component to be selected separately. We strongly recommend hearing it with your intended sources and loudspeakers, ideally followed by a home demonstration.
Rega Osiris Reference Integrated Amplifier
The Rega Osiris is Rega's flagship traditional integrated amplifier, combining a passive pre-amplifier section and high-current dual-mono power amplifier within one substantial CNC-machined aluminium case.
Its design is based around a short and uncomplicated signal path. Between the selected line-level input and the loudspeaker output, the music signal passes through the passive volume control and a single high-gain power-amplifier stage.
This approach avoids adding unnecessary active pre-amplifier stages while still providing source selection, remote volume adjustment, a record loop and Direct power-amplifier input.
The Osiris is intended for high-performance systems using carefully selected external phono stages, CD players, DACs and network streamers.
162W Dual-Mono Amplifier
The Osiris delivers 162W per channel into an 8-ohm loudspeaker load and up to 250W per channel into 4 ohms.
Its dual-mono construction provides each channel with its own dedicated transformer, smoothing capacitance and amplification circuitry.
Keeping the two channels electrically separated helps preserve stereo information and reduces interaction between the left and right channels during demanding musical passages.
- 162W per channel into 8 ohms
- 250W per channel into 4 ohms
- Dual-mono internal architecture
- Separate 400VA transformer for each channel
- 40,000µF of Rega K-Power smoothing capacitance per channel
- High-current output stage
Minimalist Passive Preamplifier Design
Unlike many integrated amplifiers, the Osiris does not use a conventional active line-level pre-amplifier stage.
Its passive pre-amplifier section selects the source and controls volume before the signal reaches the high-gain power amplifier.
This means there is only one principal amplification stage between a conventional line-level source and the connected loudspeakers.
The design is intended to minimise unnecessary circuitry, component count and signal-path complexity.
Alps Blue Velvet Volume Control
An Alps Blue Velvet motorised potentiometer controls the listening level.
The volume can be adjusted from the large front-panel control or the supplied Rega reference remote handset.
The remote mechanically rotates the front-panel control, so its position continues to represent the selected volume.
High-quality Mundorf polypropylene capacitors and signal-switching relays are used within the input path.
Fully Symmetrical Amplifier Circuit
The Osiris uses fully symmetrical circuitry throughout its main power-amplifier stage.
A common-base voltage amplifier driver stage provides the voltage swing and bandwidth needed to control the output stage while maintaining low distortion.
The cascoded differential input section uses two low-noise LED-referenced current generators.
Rega has optimised the open-loop and closed-loop feedback levels and gain-bandwidth components to support control, timing and low-frequency definition.
- Fully symmetrical power-amplifier topology
- Common-base voltage-amplifier driver stage
- Cascoded differential input amplifier
- Low-noise LED-referenced current generators
- Optimised feedback and gain-bandwidth components
- Low-inductance film output-stage resistors
High-Current Sanken Output Stage
Eight 200W Sanken output transistors are used within the Osiris high-current output stage.
The output arrangement is intended to provide the current required by large floorstanding speakers and designs with more demanding impedance behaviour.
Although the Osiris has substantial power reserves, appropriate system matching remains important. Loudspeaker sensitivity, minimum impedance, room dimensions and normal listening levels should all be considered.
Audio T can arrange demonstrations using a selection of suitable loudspeakers and may be able to organise a home demonstration depending on location and equipment availability.
Dual 400VA Toroidal Transformers
Each amplifier channel is supplied by its own custom-designed 400VA toroidal transformer.
The transformers use high-grade fully bonded core material and are mounted using a Rega-developed arrangement intended to reduce the transfer of mechanical noise into the aluminium case.
This is particularly useful where asymmetric mains distortion might otherwise cause a large transformer to produce audible mechanical vibration.
80,000µF Total Smoothing Capacitance
Each channel has 40,000µF of Rega K-Power smoothing capacitance, providing 80,000µF across the complete dual-mono amplifier.
These capacitors store energy for the output stage and help the amplifier respond to demanding musical peaks.
Fast-recovery rectifier diodes are used throughout the power supplies to reduce high-frequency switching noise.
Dedicated Low-Noise Power Supplies
The input and low-level driver sections are supplied by regulated symmetrical tracking power supplies with low-noise voltage references.
Dedicated audio supplies feed only the amplifier's audio circuits.
Input switching, the display, microcontroller and protection systems use separate supplies to reduce the possibility of control circuitry interfering with the music signal.
One Transformer-Balanced XLR Input
Input 1 is a fully balanced line-level input using XLR connections.
Rather than using an additional electronic balanced-input stage, Rega uses a purpose-designed input transformer.
This approach maintains galvanic isolation while remaining consistent with the Osiris minimalist design philosophy.
The transformer-balanced input has a sensitivity of 250mV for rated output and an input impedance of 10 kilohms.
Four Unbalanced RCA Line Inputs
Inputs 2, 3, 4 and 5 use conventional stereo RCA connections.
They can be used with line-level source equipment including:
- CD and SACD players
- Network streamers with analogue outputs
- External digital-to-analogue converters
- Moving magnet and moving coil phono stages
- Tuners
- Cassette and reel-to-reel decks
- Other compatible analogue sources
The unbalanced line inputs have a sensitivity of 220mV for rated output and an input impedance of 22 kilohms.
Balanced or Unbalanced Connection?
The best connection will depend on the source component, the design of its analogue output stage and the required cable length.
The balanced XLR input may be useful with a source that has a properly implemented balanced output or where a longer interconnect must be used.
The RCA inputs provide a simpler signal route for conventional unbalanced source components.
A balanced connection is not automatically superior. Audio T can arrange a direct comparison where the source provides both XLR and RCA outputs.
Separate Record Input and Output
The Osiris includes a separate record input and fixed-level record output for use with compatible recording equipment.
The Record output carries the source selected from Inputs 1 to 5 and is unaffected by the main volume control.
Selecting Record Monitor with the remote allows the output of a connected recorder to be heard without changing the source being recorded.
This can be used with a cassette deck, reel-to-reel machine, digital recorder or other compatible equipment.
Important Record Output Warning
The Record output is fixed level and is not controlled by the Osiris volume adjustment.
Do not connect it directly to a power amplifier or active loudspeaker without its own suitable volume control.
Direct Power-Amplifier Input
The Direct input bypasses the Osiris input selector, passive pre-amplifier section and volume control.
It provides direct access to the power amplifier and has a sensitivity of 220mV for maximum output.
The Direct input can be used with:
- A compatible external pre-amplifier
- An AV receiver with controlled front-channel preamplifier outputs
- A home cinema processor
- A source component with a reliable variable output and volume control
This allows the Osiris to power the front left and right speakers in a combined stereo and home cinema system.
Important Direct Input Warning
The Direct input completely bypasses the Osiris volume control.
Never connect a conventional fixed-level CD player, DAC, streamer or phono stage directly to this input. Doing so could immediately drive the amplifier and loudspeakers at maximum output, potentially causing equipment damage or hearing damage.
Reference Remote Control
The Osiris is supplied with a custom Rega reference remote control and two AAA batteries.
The handset provides control of:
- Volume up and down
- Mute
- Input selection
- Record monitoring
- Direct input selection
- Compatible functions on other Rega components
The remote can also operate compatible Rega products including the Isis reference CD player.
Connecting a Turntable
The Osiris does not include a moving magnet or moving coil phono stage.
A turntable must therefore be connected through a suitable external phono stage before it reaches one of the line-level inputs.
Rega Aura Reference MC
The
Rega Aura Reference MC
is the natural phono-stage partner for a reference Rega moving coil system.
It offers balanced XLR and unbalanced RCA outputs, allowing either connection type to be compared with the Osiris.
Rega Aos MC
The
Rega Aos MC
is a fully adjustable moving coil phono stage based on principles developed for the Aura.
It connects to one of the Osiris RCA line inputs and can be adjusted to suit a wide selection of moving coil cartridges.
Moving Magnet Cartridges
A moving magnet turntable requires a separate moving magnet phono stage connected to one of the Osiris line inputs.
The phono stage should be chosen to suit the cartridge and the performance level of the wider system.
Reference Vinyl Systems
Rega Planar 10
The
Rega Planar 10
can be specified with an Apheta 3 or Aphelion 2 moving coil cartridge.
Used with the Aura Reference MC, it forms a natural high-performance vinyl source for the Osiris.
Rega Naia
The
Rega Naia
is Rega's highest-performance production turntable.
The factory-fitted Aphelion 2 version, partnered with the Aura Reference MC, provides an appropriate source for a reference Osiris system.
Rega Isis Reference CD Player
The
Rega Isis CD player
was designed as the Osiris reference digital-source partner.
It can connect through the Osiris transformer-balanced XLR input or through one of the unbalanced RCA inputs.
The Isis also includes an accessible DAC section, allowing compatible external digital sources to use its conversion and analogue output circuitry.
Connecting a Reference Music Streamer
The Osiris does not include a network streamer or digital-to-analogue converter.
A separate streamer must therefore provide a compatible analogue line-level output, either from its own internal DAC or through a suitably matched external DAC.
At this system level, the quality of the streamer, DAC and analogue output stage becomes particularly important. Suitable partners include the Naim NSS 333 and the modular Innuos Stream1 and Stream3.
Naim NSS 333
The
Naim NSS 333
is a high-performance network streamer and DAC with balanced XLR and unbalanced analogue outputs.
It can connect to the Osiris transformer-balanced XLR input or to one of the four RCA line inputs.
The Osiris should remain responsible for system volume, with the NSS 333 used as a conventional line-level source.
Innuos Stream1
The
Innuos Stream1
is a modular music streamer and server that can be configured to suit the wider digital system.
When fitted with a compatible DAC board, its RCA analogue output can connect directly to one of the Osiris line inputs.
Alternatively, a digital output module can feed a separate DAC, whose analogue output then connects to the Osiris.
Innuos Stream3
The
Innuos Stream3
is Innuos' reference-grade streamer and server platform, with modular output options for different system requirements.
A suitable DAC module can provide RCA or balanced XLR analogue outputs for direct connection to the Osiris.
It can also operate as a high-performance digital transport feeding an external DAC before the signal reaches the amplifier.
Audio T can help select the most appropriate streamer, Innuos output module, external DAC and connection method for the Osiris and the rest of your system.
Connecting a Television
The Osiris has no optical, coaxial or HDMI inputs.
A television can connect only through a compatible analogue output or through a separate streamer, DAC or converter that provides a line-level analogue signal.
The Osiris does not include HDMI ARC or eARC, so television volume commands will not be transferred directly to the amplifier.
Speaker Matching
The Osiris has the power and current capability required for a broad range of high-performance standmount and floorstanding loudspeakers.
Its 250W output rating into 4 ohms makes it suitable for consideration with speakers that place substantial demands on an amplifier.
However, no amplifier is automatically the ideal partner for every loudspeaker. The following should be assessed before purchase:
- Nominal and minimum loudspeaker impedance
- Loudspeaker sensitivity
- Electrical phase behaviour
- Room size and acoustic characteristics
- Listening distance
- Normal and maximum listening volume
- Source quality and overall system balance
At this level, we strongly recommend an extended demonstration with your preferred loudspeakers and familiar music.
Protection Systems
The Osiris includes comprehensive protection intended to safeguard the amplifier and connected loudspeakers during abnormal operating conditions.
DC Protection
The output stage is monitored for excessive direct current.
If a fault is detected, the protection system can respond within milliseconds to help protect the connected loudspeakers.
Thermal Protection
If the internal temperature reaches a potentially damaging level, a thermal sensor shuts down the amplifier output.
The unit should be switched off and allowed to cool for at least 30 minutes before being used again.
Load-Line Protection
Load-line short-circuit protection limits excessive current and voltage if the loudspeaker leads are accidentally shorted.
The protection circuit is positioned outside the principal audio signal path.
Cooling and Ventilation
Heat is dispersed through the Osiris case and the substantial heatsinks positioned along both side panels.
The side heatsinks must remain exposed with enough space for air to circulate freely.
During extended high-level use, particularly with demanding loudspeakers, the amplifier can become hot. This is normal provided adequate ventilation is available.
Never place the Osiris on carpet, rugs, bedding or another soft surface, and do not cover either heatsink.
Other equipment should not be stacked directly on top of the amplifier.
Installation and Equipment Support
The Osiris weighs 25.6kg and requires a strong, level equipment shelf rated to support its weight.
Check the load capacity of the equipment rack before installation and allow sufficient space behind the amplifier for its mains lead, speaker cables and interconnects.
When using a turntable or sensitive phono stage, position the amplifier as far away from the cartridge and low-level circuitry as the interconnects reasonably allow.
Rega recommends placing other electronic components beside the Osiris rather than immediately above or below it.
No Automatic Standby
The Osiris does not include automatic standby or remote power control.
Rega explains that the amplifier needs to reach an optimum operating temperature for its bias current to stabilise.
It must be switched on and off using the front-panel power button and consumes no electricity when switched off.
Aethos, Osiris or Mercury and Solis?
Rega Aethos
The
Rega Aethos
delivers 125W per channel into 8 ohms.
It includes five RCA line inputs, headphone output, preamplifier output and Direct input within a smaller and more affordable integrated amplifier.
It is the natural alternative when the full power, transformer-balanced input and reference construction of the Osiris are not required.
Rega Osiris
The Osiris delivers 162W per channel into 8 ohms and 250W into 4 ohms from its dual-mono design.
Its passive pre-amplifier topology and single principal amplification stage provide a particularly direct route from a line-level source to the loudspeakers.
It is the choice for customers who want Rega's traditional flagship integrated amplifier.
Rega Mercury and Solis
The
Rega Mercury
and
Rega Solis
divide the pre-amplifier and power amplifier into separate cases.
The Mercury adds a DAC, USB input, headphone amplifier, display and extensive system control, while the Solis delivers 168W per channel into 8 ohms and 305W into 4 ohms.
This combination provides greater connectivity and physical isolation between the low-level and high-current circuits.
What the Rega Osiris Does Not Include
No Phono Stage
- No moving magnet phono input
- No moving coil phono input
- An external phono stage is required
No Digital Inputs
- No built-in DAC
- No optical input
- No coaxial digital input
- No USB audio input
- No HDMI ARC or eARC
No Streaming
- No network streaming
- No Wi-Fi
- No Ethernet
- No Bluetooth
- No app control
No Headphone or Preamp Output
- No headphone socket
- No variable preamplifier output
- No dedicated subwoofer output
- No second speaker-zone output
Who Is the Rega Osiris For?
A Good Choice If You:
- Want Rega's traditional flagship integrated amplifier
- Need substantial power and current delivery
- Use high-performance floorstanding loudspeakers
- Want a dual-mono amplifier with separate transformers
- Value a short and minimalist analogue signal path
- Already own suitable external phono and digital source components
- Want one transformer-balanced XLR input
- Need a Direct input for home cinema or external pre-amplifier use
- Want a separate record loop
- Have a suitable equipment rack and adequate ventilation
Consider Another Option If You:
- Need a built-in moving magnet or moving coil phono stage
- Need optical, coaxial, USB or HDMI inputs
- Want built-in network streaming or Bluetooth
- Need a headphone output
- Need a variable preamplifier or dedicated subwoofer output
- Want automatic or remote standby
- Need a compact or lightweight amplifier
- Cannot provide sufficient space around both side heatsinks
- Would prefer the flexibility of separate preamplifier and power amplifier components
Key Features
- 162W per channel into 8 ohms
- 250W per channel into 4 ohms
- Dual-mono amplifier architecture
- Passive pre-amplifier topology
- Single principal amplification stage between the input and speakers
- Fully symmetrical power-amplifier circuitry
- Common-base voltage-amplifier driver stage
- Cascoded differential input amplifier
- Eight 200W Sanken output transistors
- Triple high-current output-stage arrangement
- Two custom-designed 400VA toroidal transformers
- 40,000µF of Rega K-Power smoothing capacitance per channel
- Fast-recovery rectifier diodes
- Regulated symmetrical tracking supplies for low-level stages
- Separate supplies for switching, display and protection circuits
- One transformer-balanced XLR line input
- Four unbalanced RCA line inputs
- Separate Record input and fixed-level output
- Direct power-amplifier input
- Alps Blue Velvet motorised volume control
- Mundorf polypropylene capacitors in the input path
- Gold-plated input and loudspeaker connections
- Custom Rega reference remote control
- DC, thermal and load-line protection
- Custom CNC-machined aluminium case
- High-efficiency side heatsinks
- Rega high-current shielded mains lead included
- Lifetime limited warranty against confirmed manufacturing defects
Included Accessories
- Rega Osiris Reference Integrated Amplifier
- Custom Rega reference remote control
- Two AAA remote-control batteries
- Rega high-current fully shielded mains lead
- User documentation
Frequently Asked Questions
How powerful is the Rega Osiris?
The Osiris delivers 162W per channel into 8 ohms and up to 250W per channel into 4 ohms.
Is the Osiris an integrated amplifier?
Yes. It combines a passive pre-amplifier section and dual-mono power amplifier within one case.
What does passive pre-amplifier mean?
The source-selection and volume-control section does not add another active line-level amplification stage. The selected signal passes through the volume control before entering the high-gain power amplifier.
Does the Osiris have a built-in phono stage?
No. A turntable requires a separate moving magnet or moving coil phono stage connected to one of the line inputs.
Can I connect the Rega Aura?
Yes. The Aura Reference MC can connect through the balanced XLR input or one of the four unbalanced RCA inputs.
Does the Osiris have a built-in DAC?
No. A digital source must have an analogue output or be connected through a separate DAC.
Does it have optical, coaxial or USB inputs?
No. All standard Osiris source inputs are analogue line-level connections.
Does it include network streaming or Bluetooth?
No. A separate streamer with a suitable analogue output is required.
Can I connect a Naim NSS 333?
Yes. Its balanced XLR or unbalanced analogue output can connect to a standard Osiris input. The Osiris should control the listening volume.
Can I connect an Innuos Stream1?
Yes. A Stream1 fitted with a compatible DAC board can connect through its RCA analogue output. A digitally configured Stream1 requires a separate DAC before connection to the Osiris.
Can I connect an Innuos Stream3?
Yes. A Stream3 fitted with a suitable DAC module can connect through RCA or balanced XLR. It can also feed an external DAC using an appropriate digital output module.
Can I connect a television?
Only through a suitable analogue output or a separate DAC or streamer. The Osiris has no optical or HDMI input.
How many standard inputs does it have?
It has one balanced XLR line input and four unbalanced RCA line inputs, plus a separate Record input and Direct power-amplifier input.
Should I use XLR or RCA?
This depends on the source, cable length and system installation. Balanced operation is not automatically better, so comparing both connections is worthwhile when the source provides both.
What is the Direct input?
The Direct input bypasses the input selector and volume control, providing direct access to the Osiris power amplifier.
Can I connect a CD player to the Direct input?
No. A conventional fixed-level CD player could immediately drive the amplifier at maximum output. Use one of the normal line inputs instead.
Can the Osiris be used in a home cinema system?
Yes. Its Direct input can accept a controlled front-channel output from a compatible AV receiver or processor.
Does it have a record output?
Yes. The fixed-level Record output carries the selected source and is unaffected by the Osiris volume control.
Does the Osiris have a headphone socket?
No. A separate headphone amplifier connected to the Record output or another suitable source output is required.
Can I connect an active subwoofer?
The Osiris has no preamplifier or dedicated subwoofer output. A compatible subwoofer may be usable through high-level speaker connections, but suitability should be checked carefully.
Can the Osiris drive 4-ohm loudspeakers?
Rega specifies a maximum output of 250W per channel into 4 ohms. The speaker's complete impedance behaviour and the intended listening level should still be considered.
Does the amplifier run hot?
The side heatsinks can become hot during extended high-level use. They must remain uncovered with sufficient open space for cooling.
Can other equipment be placed on top?
No. Stacking equipment on the Osiris can restrict airflow and may affect the performance of both components.
How strong must the equipment rack be?
The shelf must be rated to support at least the Osiris 25.6kg weight, with additional capacity for any other equipment placed on the rack.
Does it include automatic standby?
No. The Osiris is switched on and off using the front-panel power button.
Is a remote control included?
Yes. A custom Rega reference remote control and two AAA batteries are supplied.
Can I arrange a demonstration?
Yes. Contact your local Audio T store to arrange a demonstration with suitable reference sources and loudspeakers.
Why Buy From Audio T?
- Specialist advice from experienced in-store teams
- Demonstrations with suitable high-performance loudspeakers
- Help comparing the Osiris with the Aethos and Mercury and Solis combination
- Reference turntable, cartridge and phono-stage advice
- Help integrating Naim NSS 333 and Innuos Stream1 or Stream3 sources
- Advice on Innuos output modules, storage and external DACs
- Balanced and unbalanced connection comparisons
- Direct input and home cinema integration guidance
- Advice on equipment supports, ventilation and installation
- Home demonstrations may be available depending on location and system requirements
- Part exchange available on suitable equipment
- Ongoing support from the UK's oldest independent specialist Hi-Fi retailer
Contact your local Audio T store
to arrange a demonstration or discuss whether the Rega Osiris is the right amplifier for your system.