I thought the best way to kick off 2017 would be to review something completely new and fresh to the site. We also thought we would go one better than giving you one product, and review two products right off the bat! Both subjects come from the loins of COS Engineering in Taiwan and sit within the digital domain. The manner in which these products both came into my possession was quite a coincidental one as well. While I was arranging a sample of COS’s new H1 direct from Taiwan, Greg over at G-Point Audio said he thinks we would really like to try the D1, of which he distributes. The two products arrived from separate locations almost simultaneously and they complete everything COS currently has to offer. What is COS by the way? Well, Connoisseur of Sound of course!

The D1 was their first release, initially available in 2014, so not exactly the newest of products. It is a DAC with the common standard function of doubling up as a pre amp and comes in pretty pricey at £7,000. I don’t have to tell you that is a lot of money to let go on a DAC but I know Greg wouldn’t waste my time with a converter unless he had really high praise for it.

The H1 is a more cost affordable solution that allows you to have a dip into COS’s ideology. It can do more tasks than D1 with the digital inputs running all the way through to balanced headphone outputs, making it a perfect candidate for us guys at Inearspace and also as a one-stop solution to go between your computer/digital source and any headphone you may own! Priced at €2,500 it still isn’t exactly entry level but is a considerable drop from the D1. Unlike the D1 it is also a brand new offering, with me having it about 3 months, gaining ownership just after its launch!

The Daddy

This is a behemoth of a product. Its sandblasted aluminium chassis gives off such a clean cut look, one that compliments my similarly finished Questyle CMA800R mono blocks all too well. Like cyclops, its face resolves all around the one big dial in the middle. At 6 cm tall and with an, even more, whopping depth of 5 cm, it really pulls in your focus when gazing upon the D1. When turned on it is flanked by 25 or so white LEDs that will let you know how much volume you are demanding, or which of the inputs you have in action. Beyond that, the D1 is a chiselled and abstract masterpiece. Corners are so precise they are sharp to touch and instead of a being a boring old block of metal, the bottom is tapered, leaving it clouded under the shade.

Going back to the volume pot because your attention just can’t go elsewhere and it actually hangs out of the main body of the D1, the part that contains all the technology. I love the feel and visual appeal of the volume knob, but something that really throws me off is that to me it operates backwards. Rotating it right decreases the volume while left gives you more, very strange! The increments are nice though, giving you 256 0.25dB steps. Because it is so large it then has been sheathed in a tombstone of a front plate. The front plate is solid metal, and pretty much 6cm thick. It weighs considerably more than the rest of the chassis and all in all we are just short of a 9kg product. This is serious gear without a doubt.

Talking more about the controls, of course, you don’t have to touch the device and can swap between inputs as well as adjust volume with the included remote, which takes on the same finish and aesthetic as the DAC itself. The similarly angled control can also fully mute the device and switch it between standby and on.

Turning the product onto its back reveals some shiny mirror like spikes that balance with needle-like precision are surely help with vibrations. Turning it round will also give off some shiny and reflective glare, this time from some impressive connectors. They are certainly not generic and don’t look like anything of the premium brands catalogues, leaving me thinking they may well be COS made from the ground up! We have RCA and XLR analogue in and outputs, meaning this can be used as an analogue only pre amp should we want to as well as being able to go from digital all the way to the analogue output… DUH! Digital input it is pretty simple, two coaxial, two optical and one USB round up the offerings and we can switch the USB between 1.0 and 2.0 to our heart’s content. 1.0 allows for driverless play back but sampling rate limitations, Josh had to use it with his PC as there was no driver, perhaps that is now fixed. I just plug and play with my MAC and it can decode all my music other than DSD, this doesn’t care for that. It may seem an oversight at the price range but it is an understandable decision to me. You also have a BUF switch that is best left on, giving digital inputs a 1-second buffer prior to conversion. In fact only turn it off for a video for the sake of lip sync.


Delving inside the unit and we have a wisely put together array of boards for both digital and analogue domains. For the digital side, we have some clever DSP and even a custom algorithm that upsamples everything to either 24/176.2 or 24/192. While traditionally I am not a fan of upsampling, especially not when forced upon me, this is all done with the desire to skip out on an IIR filter which they think will work against the phase, they go as far as saying it could corrupt it. In terms of power, both stages of the D1 are properly looked after, with a transformer dedicated to both digital and analogue. The analogue stage is built around the output of two Burr Brown PCM1792 chips that have been summed to mono and live on their own PCB boards (one per channel) that are stacked upon one another.

The Jr

The much smaller H1 still whiffs strongly of the brand image I got from their D1. Some things have been tamed a bit such as the angles not being as prevalent and the edges not being as razor sharp but we still have a very well engineered unit. You even have a front plate separate from the main chassis although at only a centimetre thick it isn’t as intimidating as on the D1. The saddest thing for me was the decision to remove the grand pot and white LED display that we had previously. Instead, we have opted for a more Yulong/Northstar esque aesthetic with a standard sized knob and a little screen to fiddle with settings. While the screen is very easy to use, it does become a less unique product because of this. While I stand by these comments this product is smart when it comes to function over form because this works well and is properly proportioned. The considerable downsizing is apt as well for its dedicated use. This is something that sits on your desk, can plug into whatever source you have, most likely a PC and will playback your music and output through some headphones or to active speakers. It is a one-stop box between your music file and listening device. It can step up and just be a standalone DAC with a CD player or music server directed into an amp, but that is holding back its full feature set.

Talking about the feature set and it has stellar connectivity. The back is filled with 4 different digital inputs, USB, optical, coaxial and an AES/EBU connection that COS had ignored in the past. Then taking inspiration from the D1 you have a BUF and USB mode switch as well as an additional line out switch. Finally, you have a single set of RCA line outputs, so no balanced for a straight shooting line level analogue output. The reality is this all a pretty standard affair for this type of headphone solution. I actually find it sad that you don’t have balanced line outs because I think when you crave more from this device I think a logical step up would be with new amplification and this as a DAC and if you buy a balanced amp, why would you not want to use its XLR inputs? What really does make me happy is that it’s clear they have put some real thought into the headphone capabilities of this product. They haven’t just decided to make a more compact DAC and throw a headphone output like so many companies do but instead have a built a fully balanced analogue section with dual 3 pin XLR outputs holding the fort down. They are those snazzy terminations as well that also double up as two 1/4 inch jacks, so you can have two cans running single ended or one pair balanced. Great versatility. I just wish you could control both pairs of headphones volumes individually when using two single ended headphones.

Because this is clearly a more ‘do it all device’, it contorts to more of the current audio trends a little better. It advertises hi-res PCM up to 24/192 and DSD64 via DoP from all of its non-USB inputs and then absolutely crushes via USB 2.0 with 32/284 PCM and DSD 128. Obviously, driverless USB 1.0 is limited to 24/96 but I know there is a PC driver for this model. It is worth noting we do have a lot of their findings with the D1 trickled down to this unit as one would hope. They still use a PCM1792A DAC chip (although just one), have that same upsampling algorithm, 1-second buffer, you get the picture, they aren’t leaving this out when it comes to their proprietary tech! While there is just one DAC chip things do split off nicely and we get two Texas Instruments LME49600s per channel for the headphone section. That would mean things were single ended until headphone section, hence the line out doesn’t have an XLR option.

Turn the page for how both products sounded….

Sonny Trigg
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    It’s really interesting that you compared the H1 with the Exogal Comet. I’m looking at both this DAC as well, and is likely going to use it to drive Stax amp-headphones. Would you give a more detailed comparison between the two?

    • Comparing the line outs of the two I find the H1 to be firmer and quicker, with less mid bass slam but a slightly more reaching depth. I also find the H1 to be the clearer and more open sounding DAC. I think the COS is technically better! That being said as Stax are generally quite open and quick to begin with, you may like that extra richness and warmth from the Comet?