Portable amp with everything but the kitchen sink!
PROS: dual Solid State and Vacuum Tubes timbre, Class A and AB amplification mode, dual LINE and Pre-AMP input modes, 3.5mm SE and 4.4mm BAL for input/output, removable rechargeable 18650 batteries, included interconnect cables.
CONS: price, hissing with sensitive iems (just needs iematch).
The product was provided to me free of charge for the review purpose in exchange for my honest opinion.
Some of you are probably going to find it a bit surprising that I’m reviewing an amplifier. I had to take a walk down the memory lane, trying to remember the last time I tested portable amps, just to realize it was 6 years ago, and coincidentally one of them was Cayin C5. Back then DAPs were not as powerful, their internal amp sections were more basic, and battery life was subpar, thus using external amp was beneficial to boost output power and to extend battery life of your portable source. But you also had to compromise the portability of your setup.
Then, DAPs evolved, becoming more powerful and more advanced, with some of the manufacturers offering modular design solutions with interchangeable amp modules or more advance interchangeable DAC/amp cards like in N6ii. It all comes down to having more choices and being able to use your favorite source with different sound-shaping options. And speaking of more options, another example would be N3Pro and N8 from Cayin where you don’t even have to replace the module, just switch from Solid State to Tube.
So, what is next for Cayin after DAPs with Solid State and Tube timbre or DAC/amp cards with Class A/AB amp modes? The announcement of A02 module for N6ii with Line Out only output was a big clue. At first some were confused about release of LO only card without headphone output, just to realize later that A02 was a preamble to the upcoming C9 portable amplifier. I was skeptical at first, thinking why do I need external amp, regardless of its advanced design. But this skepticism turned into a bit of an obsession in the last few weeks. Here is more about it.
Unboxing and Accessories.
The unboxing experience of C9 reminded me of the premium IEM packaging. The giftbox quality packaging box had a magnetic top cover to reveal a non-removable foam insert with a secure cutout for C9 and another magnetic side door for a sliding tray with accessories. I know, some will say, what is a big deal. But I found it to be very convenient to access the accessories without digging through and removing layers inside of the storage box.
In addition to the main attraction, C9 with its battery module already mounted inside, other accessories include pure copper single ended (3.5mm to 3.5mm, CS-35C35) and balanced (4.4mm to 4.4mm, CS-44C44) interconnect short cables, usb type-c charging cable, a capsule with 4 spare screws for a battery module and T6 screwdriver. Plus, you will find a user manual and rear panel glass protector.
The overall dimensions of C9 are 160x80x28mm with a weight of 550g. It’s a rectangular box, borderline on being portable/transportable due to its weight and considering it has to be stacked with a source (if you go with a DAP). A big part of its weight and the size is due to internal battery module and 4x included Sony VTC6 18650 batteries (3000mAh, 3.7V). The battery module tray alone has a weight of 282g and extends 82mm in length. Thus, half of the length and the weight of C9 is due to its 4x rechargeable 18650 premium batteries inside of a module tray.
The back of C9 has usb type-c connector for charging of batteries, and it supports anything from a standard 5V/2A charger to a higher voltage fast PD or QC3.0 chargers which cut down the charging time by almost a half from 6hrs to 3hrs. Also, next to usb connector you have 4 battery status LEDs to indicate charging status and remaining battery capacity. The unit is fully charged when all 4 LEDs are solid and stop blinking. Both, usb connector and LEDs, are part of the removable charging battery tray which you can use standalone for charging. Of course, you can buy your own battery charger, but Cayin will be offering spare charging tray for sale soon which should make it very convenient to be able to charge another set of batteries outside of C9 and then just slide in and out a new tray.
The bottom of the C9 has a glass surface with a protective film that was already applied on my review unit. I would have loved to see included some stick-on rubber feet to make sure the amp doesn’t slide across the surface. The top of C9 was crafted with two glass oval shaped “eye” openings to reveal a pair of Korg NuTube directly heated triode vacuum tubes when in use. The right side doesn’t have anything, and the left side has a Pre-Amp activation button, used as a safety measure in addition to Line/Pre-Amp switch. You will have to press and hold this button for 3sec until the blue led indicator next to it lit up, letting you know that Pre-Amp input mode is activated.
The front of the C9 is where you will find all the ports and switches placed around the volume wheel in the middle. The volume wheel, which controls 4-channel ALPS potentiometer, is 15mm in diameter and rotates clockwise to raise the volume and counterclockwise to lower it. The knob of the wheel is flush with the front of the C9 to prevent accidental turning, and easily accessible from the top through a generous cutout to be able to turn its diamond-cut wheel knob. The rotation of the wheel has a fluid motion and a nice resistance, just enough so you don’t turn the wheel by accident, and still easy to operate with a thumb.
Looking closer at the front of C9, you will find at the top left corner Line (controls output with volume wheel) and Pre-Amp (output is set to fixed level and you control the input to C9 from the source) input mode switch, H/L gain switch (6dB boost), Solid Stage (quad set of Toshiba 25K209 JFETs) or Tube (Korg NuTube 6P1 vacuum tubes) timbre switch, and Class A and AB (dual amplification operation – DAO) mode switch. In the lower left corner, you have Input ports, 3.5mm SE and 4.4mm BAL, and in the right corner you have Output ports, 3.5mm SE and 4.4mm BAL with a design allowing you to mix SE to SE, BAL to BAL, SE to BAL, and BAL to SE. In the middle of the front under the volume wheel you will find a power button with a status LED that blinks for a few seconds when you turn C9 on when controller initializes the device, and also when you switch between Solid State and Tube timbre.