Cayin C9 Review

Cayin Audio C9


As we’ve discussed already in the features, the Cayin C9 is a very versatile unit, giving you many different options for tuning the sound to your liking.

First of all there’s the Class A vs Class AB mode. According to Cayin the Class A mode offers low efficiency and low distortion. It’s supposed to sound musical, smooth, warm and lush. Vocals are strongest here. In the Class AB mode you according to the Cayin team get higher efficiency and dynamics. The sound is supposed to be clean, tight and extended. The AB Mode has authoritative slam and liveliness.

Of course we’ll be checking out the sound of both of these options in the next chapters, as well as the difference between the solid state and tube timbre.

As explained as well, the C9 has a line and pre-amp mode. With the line mode you receive a fixed voltage audio signal from line level output and the C9 functions as a headphone amplifier with local volume control. In pre-amp mode the C9 receives variable voltage audio signal from the pre-amp output and the C9 functions as a power amplifier where the volume is controlled at the source.

And last but not least there are two gain stages: Low gain vs High gain (MCU controlled and automatically optimized).


Sound – Intro

The Cayin C9 is designed as a portable amplifier but I often ended up using a full-sized headphones when I was using the C9 in my office, hooked up to the Violectric V590’s output. IEM-wise (on the go with the SP2000 or HiBy R8 as source) I have tried many different units but there isn’t really one technology I prefer over the other. The C9 works great for dynamic drivers, balanced drivers, planar magnetic drivers, EST drivers and hybrids combining all of them.

With the ALPS volume pot and the electrical volume control there is no channel imbalance whatsoever, not even with the most sensitive IEMs. The noise floor is also very low, in all four possible combinations. With no music playing your most sensitive IEMs will display a bit of noise (especially in pre mode) but it’s really at a very low volume, and one you start playing music, even at low volumes, this isn’t audible in any way. At least not in my experience.

For this part on sound, we’ll split up the sound in several parts. General, SS A, SS AB, Tube A, Tube AB, and balanced vs Single ended. We have used the Cayin C9 with many different sources (both desktop as well as portable), IEMs and headphones.

Cayin Audio C9

Sound – General

To me the typical Cayin house sound is present here and that’s a good thing. You get a really natural presentation, with a full bodied presence from top to bottom. The lower regions, as is very often the case with Cayin, have good weight, presence and come delivered with a powerful impact.

You overall get good clarity and cleanness, excellent speed and a high level of musicality. The mids have a lovely timbre and natural presence, while the top end is easy going, yet energetic and dynamic. Depending on the configuration chosen the characteristics of the tuning will change, and we’ll go into detail about that in the next chapter.

No matter the output chose, the spaciousness and separation are good as well as the level of detail. As you’ll see, it’s impossible to say which output sounds the very best as they are all different and have their own strengths. Depending on the ear or headphone used I very often switch between the different outputs. As it only takes a flick of a switch, it’s very easy to hear the difference and select the best setting. That exactly is one of the incredible strengths of this amplifier: you can finetune the sound depending on your mood of the moment or the ear/headphone in use. Can it get any better?

The quality of sound in all settings is high and very good. As a portable amplifier it’s nothing short from impressive. And even as a desktop amp, it’s ahead of many full-sized desktop amps. Of course when switching to say the V590 amplification section or the Headonia for tubes, there still is quite a bit of improvement at all levels, especially the micro detail (precision), note richness, decay and layering. But we’re talking about high end desktop gear here. If you compare the Cayin C9 to the portable competition, it’s a whole different story. Oh yes, let’s continue and find out!

Cayin Audio C9

Sound – Solid State

Class A

For me the Class A is the most refined and natural sounding output of both. You get a more relaxed and natural sound, with a sense of smoothness from top to bottom. It’s also the most spacious of both options and the decay and note timbre in the mids here, for me is at its best.

Overall you get a more neutral tuning, but the delivery is smooth and with some mid-warmth both in bass and mids added to it. It’s incredibly easy and fun to listen to. The treble section is dynamic and has enough energy to keep everything exciting, yet realistic.

The Class A output of the solid state setting is very easy to listen to, with great pace and nice timbre. The vocals are somewhat more forward but excellent.

If you listen to nicely balanced ear or headphones, then this will probably be the most interesting setting for you. It’s a settings I often listen to with many different type of IEMs.

Cayin Audio C9

Class AB

The Class AB setting to me is bigger and bolder. It’s the more direct “in your face” approach in regards to its delivery. It’s less refined, precise and spacious sounding but it has more impact and there’s more contrast between the bass and highs.

The biggest difference for me is the way everything is presented. It’s cooler, less smooth and less spacious. The mids are less present compared to Class A and as a result the focus is more on the bass and treble part.

All-in-all it to my ears it is less refined than the Class A output, but better in regards to presence and bass/treble contrast.  When your ear or headphone doesn’t excel in these areas, this is the setting to go for.

The part on sound continues on the third page of this review. Click here or use the jumps below.

4.4/5 - (182 votes)


Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply March 16, 2021


    Um the broadway seems very similar in price, its battery powered amp with no dac. Seems like a pretty obvious comparison.

    • Reply March 16, 2021


      If you read both reviews you will have noticed a different writing style. That’s right, different reviewers. So um, these units are in different countries 😉

      And the Broadway isn’t really (trans)portable, is it? It’s a very special niche

  • Reply March 17, 2021


    How true is shaping sound by ‘battery rolling’, is that a thing?

  • Reply June 19, 2021

    Tim B.

    What be the Best DAPs to pair with the Cayin C9 at this time.

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