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How To Retrofit USB Inputs to a DAC or Digital Amplifier

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Unfortunately, since their invention, many digital to analogue converters, including home stereo digital amps, were released without readily equipped USB inputs. It seems that, a couple of years ago, manufacturers didn’t consider computer audio when they developed these products. In any case, I am still pretty disappointed to see brand new, top-of-the-range DACs being released without USB ports. I simply don’t understand why digital audio manufacturers still skimp on USB inputs.

Thankfully, this is easy to fix. You can retrofit USB inputs to virtually any DAC available with an external device called a ‘USB to SP/DIF converter.’ The acronym SP/DIF represents a traditional digital audio signal. SP/DIF inputs are basically coaxial (RCA/BNC) or optical inputs on devices that receive a digital signal from a DVD player, BlueRay player or just about anything that outputs sound in a digital format. So, in order to retrofit our USB input, we simply need a device that translates USB from your computer and transforms it into something that can be digested by your DAC in coaxial or optical form. One major downside, however, is that you are going to lose one digital input. In addition, USB to SP/DIF converters sometimes need an extra power supply to enable them to run effectively.

To connect a USB to SP/DIF converter, simply connect the USB to your computer and use a standard digital audio cable to connect the converter to your DAC. It doesn’t need to be fancy equipment, simply ensure that it is designed for digital audio with a 75 Ohms impedance. Personally, I buy my cables at BlueJeansCables.com but you can choose your preferred retailer.

To ensure the best quality, I highly recommend that you get a USB to SP/DIF converter that operates in asynchronous mode. Asynchronous operation means that your DAC requests data from your computer or laptop as and when it is needed and doesn’t rely on your laptop shoveling data to the DAC when it has superfluous processing time. A good indication that your USB to SP/DIF will function effectively is that it comes with the appropriate drivers for your preferred operating system.


If you are an audiophile with high quality expectations, I personally recommend the excellent Hiface Two USB converter which is made by the small Italian manufacturer M2Tech. Alternatively, consider the top-notch Singer SU-1 USB DDC.

Although it is priced at around 200 Euros, you get state-of-the-art performance that is even capable of transmitting high-resolution, bit-perfect audio up to 24bits/192kHz. M2Tech’s converter supports Windows, OS X and, I believe, even major Linux distribution through non-proprietary drivers. So far I have used the Hiface Two with Windows and foobar2000 and I have not encountered any problems. It also works effectively in tandem with Audirvana on my Mac; simply select the Hiface Two as the output driver and the task is done. Remember, each Hiface ships with a choice of BNC or Coax termination so pick one that works appropriately with your DAC.

M2Tech also make a high-end version of the Hiface Two which comes in three separate boxes (converter, power supply and clock). However, this three-part product’s price is driven up to around 1000 Euros. I have tested the Evo product line but decided that the performance gains were simply too minimal for the manufacturers asking price.

If the Hiface seems too expensive, grab a Behringer UCA202 for under 30 Euros from Amazon.com. While you won’t get exactly the same performance as the Hiface due to the Behringer’s lesser parts and simple design, you can output a pristine bit-perfect digital audio signal anywhere up to 48kHz, albeit not asynchronously. As a result, you are not going to be able to play your 24bit FLAC files without downsampling. However, for the cheaper price, it is a solid performer and I have not encountered any complaints about it yet.

The Behringer also comes with an optical output to boot which the Hiface lacks. Heck, I would even purchase the inexpensive Behringer in addition to the Hiface just for the ability to produce an optical output signal. The Behringer itself operates entirely without drivers. Use it on either Windows, Mac or Linux systems and it will work effectively, simply plug and play.


It’s easy to see which product champions the price to performance contest. The Behringer is my recommendation for cost-conscious applications those where an optical output is mandatory. On the other hand, If you desire optimal sound quality input to your megabuck stereo system, you definitely cannot go wrong with the M2Tech Hiface Two.

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  • Angus September 8, 2016, 08:08

    Are these still your recommendations for USB to coaxial?
    Are there cheaper asynchronous models?

    • Michael September 8, 2016, 09:10

      I haven’t researched this topic for a while but yes, there are cheaper Chinese converters popping up all over the place (especially eBay). Check for Breeze Audio units.