Rega Osiris Integrated Amplifier

The Osiris is the culmination of Rega's 32 years of solid-state amplifier development — a reference-level, 162-watt dual mono integrated amplifier housed in a custom CNC-machined aluminium case. It represents Rega's answer to the question of what a no-compromise integrated amplifier looks like when circuit simplicity is the primary design philosophy.

That philosophy is expressed most clearly in the pre-amplifier section. The Osiris uses a passive pre-amplifier topology with a passive volume control and a single power amplification stage. There are no active gain stages in the pre-amplifier. Signal passes through the passive volume control directly to the power amplifier input, with nothing in between to add colour, compression, or distortion. It is an unusual approach for an integrated amplifier — and it is a deliberate one. At this level of power supply quality and output stage design, Rega believes a passive pre-amplifier is the correct solution.

Where the Osiris Sits in the Rega Range

The Osiris is the flagship of the Rega integrated amplifier range, sitting above the Aethos. For those who prefer separates, the Mercury pre-amplifier and Solis power amplifier represent Rega's most advanced electronics.

The step up from the Aethos involves several meaningful changes. First, power: 162 watts per channel into 8 ohms, rising to 250 watts into 4 ohms — figures that reflect the mass of the Osiris's power supply rather than simply higher-rated transistors. Second, the power supply itself: the Osiris uses two purpose-designed 400VA toroidal transformers, one per channel, with 40,000 microfarads of K-Power smoothing capacitors per channel. The Aethos uses a single custom-wound toroidal; the Osiris doubles the supply for complete channel independence.

Third, the output stage: eight Sanken 200-watt output transistors in a triple high-current configuration — four pairs per channel, capable of delivering the current demanded by any speaker load with reserves to spare. And fourth: the balanced XLR input, which allows the Osiris to accept fully balanced sources and reject common-mode noise at the input stage.

Sound and Performance

The passive pre-amplifier is the defining characteristic of the Osiris, and it is worth understanding what that means in practice. An active pre-amplifier stage — with gain transistors, capacitors, and feedback loops — inevitably adds some of its own character to the signal. A well-designed one adds very little; a passive pre-amplifier, properly implemented, adds none. The signal level reaching the power amplifier input is controlled entirely by the passive volume control, with no active processing in between.

This approach works because the Osiris's power amplifier section has sufficient gain to produce full output from the passive pre-amp level. The low-distortion common-base voltage amplifier driver stage, with its symmetrical circuit topology and two low-noise LED-referenced current generators, takes the passive pre-amp output and amplifies it with a minimalist signal path. The result is an amplifier with a measured THD and noise below 0.05% — not because aggressive feedback has reduced measured distortion at the expense of character, but because the circuit is simply clean.

The eight Sanken output transistors, in their triple high-current configuration, deliver current to demanding speakers with the ease that comes from massive reserves. At 250 watts into 4 ohms — where many speakers actually operate at frequency extremes — the Osiris does not contract. It maintains dynamic authority at the levels that reveal whether an amplifier has genuinely good power supply design or merely adequate specifications.

What this produces in listening terms is an amplifier that is essentially invisible. The Osiris does not impose a house sound; it presents what the source delivers, with the dynamic authority and resolution to make the differences between sources audible.

Build Quality and Design

The Osiris is CNC-machined from aluminium — a level of chassis construction that is reserved for reference components, and that is itself part of the engineering. An aluminium chassis is more dimensionally stable than steel, and CNC machining ensures the accuracy of component mounting and the integrity of the enclosure.

At 25.6kg, the Osiris announces its power supply design through its weight. The two 400VA toroidal transformers, the capacitor banks, and the output stage heatsinks account for most of that mass. Dimensions of 434 × 122 × 350mm make it a substantial unit; it needs a proper equipment stand rather than a shelf.

The CNC remote handset — a reference-quality control rather than the standard Solaris remote — and the reference mains power lead are included. Fast-recovery rectifier diodes throughout the power supply are specified for lower noise; the two toroidal transformers use an innovative mounting technique that eliminates noise transfer to the chassis. Lifetime warranty against manufacturing defects applies.

Connectivity and System Matching

The Osiris provides four line-level RCA inputs, one balanced XLR input, a direct input, and a record output. There is no phono stage and no digital input. The passive pre-amplifier topology means the Osiris requires sources with adequate output levels — most modern source components (CD players, DACs, streamers) are directly compatible.

At this level, sources should match the Osiris's performance. The Rega AOS MC Phono Stage and a Planar 10 or Naia turntable are the natural analogue sources. The balanced XLR input allows a fully balanced DAC or streaming device to connect with maximum noise rejection.

Speaker matching at 162–250 watts is essentially unrestricted. The Osiris will drive any passive loudspeaker load — including electrostatically demanding speakers and large floorstanders with low sensitivity — without difficulty. The practical limit is not the amplifier's capability but the listener's budget for speakers that can reveal what the Osiris offers. Dave or Chris at Martin's can advise on pairings at this level.

Technical Specifications

Who Is It For?

The Osiris is for the listener who wants the reference Rega integrated amplifier — who has sources, phono stage, and speakers capable of resolving what 162 watts from a passive pre-amplifier delivers. It is the right choice for a Planar 10 or Naia owner at the electronics end of a reference system. Those who prefer separates should look at the Mercury and Solis; those who still need a phono stage or DAC in their integrated amplifier should look at the Aethos and add dedicated external sources alongside it.

Buying from Martin's Hi-Fi

Martin's Hi-Fi has been in Norwich since 1968, and the Rega range has been part of what we do for years. We are still family-run — Elizabeth Gould runs the business today — and we stock only brands we have heard properly and stand behind.

The Osiris is available to hear in our Norwich showroom; call ahead and Dave or Chris will have it set up in a properly matched system so you can hear what the passive pre-amplifier topology and dual-transformer power supply genuinely offer. This is an amplifier that deserves a listening session before purchase.

Reach them at [email protected], [email protected], [email protected], call on 01603 627010, or WhatsApp Dave or Chris directly on 07554 687137 for a quick answer after your purchase. You can read more about who we are and how we work on our Why Martin's page. We are at 85–91 Ber Street, Norwich, NR1 3EY, open six days a week.

Contact: [email protected] | 01603 627010 | WhatsApp: 07554 687137 | 85–91 Ber Street, Norwich, NR1 3EY