June 2020

Rega Aethos Integrated Amplifier Review
Rega moves to fill a key space in its amplifier range with the Aethos, an unusual exercise in 'trickle up' engineering. 
Review By Ed Selly Of HIFICRITIC

  Over the last eighteen months, the main focus of Rega Research's activities has been its range of turntables, cartridges and phono stages. While hardly surprising, this has but it meant that the range of supporting amplifiers no longer matched the turntables as closely as they once had. In particular, the significant hole between the £1679 Elicit R and the £6399 Osiris was an issue for people looking to partner the Rega Planar 8 or 10 with a matching Rega amplifier.

To fill that gap, Rega has launched the Aethos. At £2999, it sits roughly equidistant between the two existing amplifiers, and rather than taking the Osiris and stripping it back, it is instead a beefed up version of the Elicit R. Terry Bateman, responsible for the Aethos and the rest of Rega's electronics, designs even gave it the development code '1600E', in reference to that range-topping variant of the Ford Cortina with all the bells and whistles on it.

The Aethos isn't simply an Elicit R in a hefty box: while its power output is quoted at 125W into eight ohms – a rise of 20W over the smaller amp – the key difference isn't the bald number but the implementation. The output stage now features a quartet of 160W Sanken Darlington transistors rather than a pair, as part of a low source impedance emitter follower Class-A driver stage. Rega says this enables the Aethos to deliver its quoted output without any significant strain on the components.

Another aspect of the design borrowed from the Elicit R – and very distinctively Rega – is the volume control. This changes both input and feedback levels, Rega saying this helps improve the level consistency between channels while reducing noise and input overload at the same time.

Using this volume control is a mixture of good and mildly infuriating: the channel balance does seem to be exceptionally good, even at extremely low levels, but less satisfactory is the enormous change in gain available in less than a quarter of a rotation. Add in a remote motor that doesn't happily make fine adjustments and you have an amp on which it can be tricky to set the correct listening level, particularly with sensitive speakers.

The Aethos is not equipped with an internal phono stage which, at first glance, seems like a curious decision from a company that sells so many turntables, especially at a time when rivals such as Naim are busy reinstating phono capability after years of being line-only. However, the internal volume of the Aethos is 'full', with no location where a phono stage could easily be placed and enjoy a degree of isolation from the other sections. This is compounded by the fact that turntables suited to pairing with the Aethos are likely to use moving coil cartridges, further increasing the engineering challenges of a phono stage. Rega continues to make a selection of external options, however.

The Aethos has five line inputs, a tape loop (with parallel outputs so you can drive a headphone amp and record at the same time), a power amp in and preamp out, while the speaker outputs are are partnered with a headphone amp feeding a 6.35mm socket.

Heavy Metal
The new casework design mixes influences from both the pricier Osiris and the more affordable components: immensely hefty for an amplifier at this price, it makes a major contribution to an all-up mass of over 17 kilos. It is beautifully finished and feels exceptionally solid: Rega has already begun the process of ensuring that devices likely to be partnered with it are fitted with matching casework.

There are, however, some minor operational quirks. There's no direct input selection: instead you have to cycle through them, although you can at least cycle in both directions. What's more, the supplied 'Solaris' remote handset is also fairly long in the tooth, and festooned with buttons no longer relevant to the control of the Aethos, although it does work pretty much regardless of where you point it, which is welcome.

The review sample had plenty of hours on it, so t was immediately connected to a Chord Electronics Mscaler / Hugo TT2 combination and a pair of Focal Kanta No1 speakers – a design sensitive enough to demonstrate the limitations of that volume adjustment. The most immediately identifiable trait was a consistent sweetness across the upper registers, encouraging the listener to push the level even when listening to music that can demonstrate an 'edge' when pushed. The title track of Jack Savoretti's Written in Scars keeps its urgency and passion but it does so without exposing the limitations in the mastering. Even via the Focals, which can be a little unforgiving, the Rega is usefully controlled – and some experimentation with other speakers suggests that this behavior is consistent.

The piano in the newly-released Empty by Nils Frahm is reproduced in a very believable manner: notes are crisply defined and the manner in which they decay natural and unforced. Frahm's fidgeting is very much part of the recording, something that the Aethos does a fine job of resolving: the little creaks as he shifts position and the noise of the keys are easy to discern, but feel organically part of the recording itself and not a distraction from it.

Narrow Soundstage
Where the Aethos is slightly less assured is the soundstage it creates around the piano. The presentation sits between the speakers with little perception of it extending beyond them. This can make some larger and airier recordings sound narrower than they do on some rivals, but the Rega uses the space it does create to ensure that the presentation is ordered and understandable. It also means that smaller, more intimate recordings like Bill Fay's Countless Branches are handled very well: the deliberately constrained production of In Human Hands is fabulously involving.

The Aethos really excels with more dynamic material: beyond the bald numbers of its power output it delivers a consistently muscular performance, most apparent in the bass response. The huge drum struck at intervals in Fink's live performance of Sort Of Revolution is felt as much as heard, even with the relatively compact Focals connected. Crucially, this is not a blunt instrument but something that the Rega wields with impressive dexterity: everything starts and stops with precision and the integration of this hefty bass response with the rest of the frequency range is seamless, making the low end it the natural limit of the overall response rather than feeling artificially augmented.

This combination of speed and temporal accuracy means that Aethos is very entertaining as the tempo increases, positively reveling in the 24-bit/96kHz version of Steve Miller Band's Fly Like an Eagle on Qobuz. It's hard to listen to the Aethos for any length of time with material like this and not be in some way emotionally engaged by it: the combination of strong timing and those sweet upper registers makes for an amp that will take even the most rough and ready material and find the joy in it. Intersperse this with much more relaxed music and the amplifier never feels in any way forced or unnatural at any stage.

Line-only it may be, but the Aethos is an excellent partner for turntables: connecting Rega's Planar 10 via a Cyrus Phono Signature phono stage produces a combination greater than the virtues of the two devices on their own. Listening to Poppy Ackroyd's Resolve; a fascinating, multi layered piece of modern classical piano, the Planar 10 adds some welcome soundstage width. Provided the phono stage that sits between the two devices is well matched in presentation terms, the combination of the Planar 10's exceptional detail retrieval and tonal accuracy with the refinement of the Aethos is a genuinely impressive partnership.

Impressive With Headphones, Too
The headphone stage is also worthy of note. Using a pair of Audio Technical ATH-A2000Z headphones – not a terribly demanding electrical load but fairly easy to provoke with an overly bright or forward source – the Rega partners up very effectively. The same basic tonal balance that the Aethos demonstrates via the speaker terminals is applicable here too but, just as when partnering the Aethos with the Planar 10, there is a slightly greater perception of width with large-scale material.

What's also important is that the headphone amp never feels like a mere convenience feature or something added to ensure a box is ticked on a comparison table. The Aethos stands comparison to dedicated headphone amplifiers up to a few hundred pounds in price, making it potentially strong value for customers that do a fair bit of listening buttoned up.

In fact, 'strong value' is a useful two word summary for the Aethos in general. Thanks to that burly casework, it feels like a lot of amp for the asking price and that perception is only enhanced when you listen to it. This is an amp that produces a sound that fundamentally engages the listener and delivers on the emotional aspect of music exceptionally well. There is no shortage of price-competition, but Rega has delivered an amplifier foregoing an overly elaborate specification to focus on pure audio performance – the result is something that should be on any purchasing shortlist at the price.

Specifications
Type: Solid-state stereo integrated amplifier
Power Output:125 Watts at 8 Ohms (156 W at 6 Ohms)
Headphone Output: 32 Ohm 2.7 V, 54 Ohm 4 V, and 300 Ohm 9 V
Source impedance 109 Ohm
Preamplifier Output: 840 mV
Input Sensitivity: 224 mV at 17 k Ohm
Direct Input: 840 mV at 50 k Ohm
Power amplifier gain 31.6 dB
Frequency Response: 10 Hz to 30 kHz
THD+Noise: Typically 0.007% @ 1kHz 
Dimensions: 433 x 95 x 360mm (WxDxH including speaker terminals)
Weight 17.5 kg
Price: £2999

Manufacturer
Rega Research Limited 
Website: www.rega.co.uk

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