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Cayin RU6 Review – Oldschool Cool

Comparisons –

Hidizs S9 Pro ($119): The S9 Pro is a personal favourite dongle, it too has a notable soundstage and driving power advantage over many competitors. The RU6 provides a slightly more affirmative sub-bass slam combined with a fuller, smoother mid-bass that delivers a more textured note presentation. The S9 Pro is contrarily more linear. It has a cleaner tonality with a more defined note structure and greater separation in the mid-bass especially. This character continues through the midrange where the RU6 is slightly lusher and fuller while the S9 Pro is one step more revealing with a more neutral tone and body.

The RU6 has a slightly more natural timbre and layers better while the S9 Pro picks up a little more fine detail. Up top, the S9 Pro has a slightly sharper transient response combined with a more present treble in general. It has a brighter background and is slightly more detailed. The RU6 once again offers the more natural tonality and free-flowing note presentation. It sounds smoother and more refined with a little more headroom overall. The RU6 definitely has a wider stage and its imaging is more involving. The S9 Pro sounds sharper in its direction and has a stronger centre image. It offers a narrower albeit slightly deeper stage and has the advantage on separation.

Astell & Kern Dual DAC ($149): The Dual DAC offers a similar style of natural tonality and very impressive dark background albeit noticeably scaled back and at a lower cost – you will notice this less on IEMs than headphones as I believe the Amp section here is most divisive. The RU6 immediately has a driving power advantage, its bass extends deeper and slams harder. The RU6 has a slightly bigger bass overall but the Dual DAC has similar mid-bass fullness and smooth character. This continues to the midrange too where both showcase a slightly denser, smoother presentation. The RU6 has slightly larger vocals, it sounds more powerful and filled-in. The Dual DAC offers a slightly cleaner tonality with a similar coherent character.

Under scrutiny, the RU6 does resolve a little more nuance, but both layer and present strikingly similar at a surface level. The Dual DAC has a slightly more balanced treble presence and more bite in the lower treble with a slightly sharper transient response. Altogether, this enables it to resolve fine detail slightly better. Meanwhile, the RU6 is smoother and more refined, delivering a bit more texture and body. The RU6 has a slightly wider stage and a bit more depth too. It has more immersive imaging while the Dual DAC has slightly sharper positioning.

Earmen Sparrow ($199): The RU6 offers a slightly fuller and deeper-extending sub-bass albeit the Sparrow is notably tighter in its delivery. Where the RU6 is smooth and relaxed with a less technical nature, the Sparrow is tight, defined and separated. As it has a lick of deep-bass emphasis granting a bolder note structure, it retains admirable dynamics and power on top. The midrange is slightly more contrasted on the Sparrow delivering a more articulate, separated and revealing voicing. Meanwhile, the RU6 is more coherent with greater body, warmth and smoothness. It should be reinforced that neither source sounds overtly coloured here but do lie on opposites ends of the spectrum in terms of approach to colouration.

I am hearing a slightly more etched presentation on the Sparrow. It is slightly more layered and offers higher clarity. The RU6 offers a more natural note presentation, being noticeably more forgiving and just as spacious. It has a more relaxed and complete note presentation. The top-end is more present on the Sparrow and this contributes to its articulate nature. This is especially so in the lower-treble. The RU6 has a more natural timbre with more wholly resolved notes with better body and texture. The Sparrow also doesn’t have quite the same headroom. Both offer similar soundstage width and depth. The difference mostly lies in imaging with the Sparrow having more layers and better separation, the RU6 pushing being floatier with more contrast between foreground and background.

Verdict –

I do believe many modern sources are becoming highly homogenous which is not necessarily a bad thing. However, this does mean that the RU6 is both an accessible gateway to a proper R-2R sound and one with no direct competitors. While often the raw hardware doesn’t constitute the entire experience, here it does feel like it is imbuing a very distinct character. It’s a completely innocuous style of colouration that is very easy to like so long as you aren’t expecting boosted clarity or the highest note definition and micro-detail retrieval. Moreover, it does so with a very respectable amp section sporting balanced output, a black noise floor and a low output impedance. This makes it suitable for both IEMs and very serviceable for a good selection of headphones too. The tonality is natural and highly coherent yet balanced enough not to complicate pairings. Enthusiasts will be sure to enjoy the RU6’s wide stage and analogue-like note presentation that grant it one of the sweetest and most euphonic sounds I’ve encountered from a portable source yet.

The RU6 is available from MusicTeck (US) for $249.99 USD at the time of writing. I am not affiliated with Cayin or MusicTek and make no earnings from purchases through these links.

Track List – 

Billie Eilish – dont smile at me

Bob Seger – Night Moves

Courtney Barnett – Rae Street

Cream – Wheels of Fire

Dire Straits – Communique

Dirty Loops – Next To You

Eagles – Hotel California

Elton John – Honky Chateau

Fleetwood Mac – Rumours

H.E.R – I Used To Know Her

Jasen – BYE

John Mayer – Continuum

Kanye West – Ye

Missy Higgins – The Sound of White

Radiohead – OK Computer

TALA – ain’t leavin` without you

The Beatles – Abbey Road

The weeknd – After Hours

Vampire Weekend – Father of the Bride

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