Network Streamers

Network Streamer

Today musical content is mainly accessed through digital formats, so it makes sense to have a network streamer where you can access entire digital musical libraries in a matter of milliseconds. Music streamers are a relatively new concept and still quite expensive, typically ranging from around $500 to $5,000 dollars. On top of that, if you want access to features like parametric EQ, you often have to pay an additional monthly fee for software such as Roon.

My goal is to build or buy a low-cost streaming solution. My parameters are support for common streaming platforms in addition to utilize parametric EQ. I also want any modifications to the line level audio signal to happen in digital space to avoid multiple ADC/DAC conversions. Finally I want support for multi-room audio. The full list of opinionated requirements are here.

  1. Spotify connect support
  2. Airplay & Bluetooth
  3. Parametric EQ
  4. UI for web and mobile
  5. Multi-room support

Almost all of the streaming options available under $500 involve the use of a Raspberry PI or similar card-computer style platform. While card-computers are an affordable option, there are very few packages that offer all the functionality that I’m looking for. For those interested in bare-metal installs of software on a Raspberry PI you can use the free software Rune. The Rune software supports requirements 1 and 2, however lacks in the other areas. Another option is to install Spotify connect compatible software (ie: librespot) directly on an RPI. While this works, it’s a bit bare bones and offers minimal control to the operator.

For more advanced functionality there are black box solutions like the miniDSP 2x4 HD - however this device focuses primarily on the DSP component and none of the streaming functionality. Additionally because the miniDSP converts analog input to the digital domain before applying DSP and converts back to analog output, you are at the mercy of the device’s ADC/DAC capabilities, which are not world-class.

HiFiBerry DAC+ DSP
Figure 1. HiFiBerry DAC+ DSP

Then there’s the HiFiBerry DAC+ DSP. The DAC+ DSP is a Raspberry Pi hat that offers DAC functionality in addition to onboard DSP. The DAC+ DSP also supports streaming from Spotify Connect as well as supporting optical input/out, which satisfies the requirement of keeping line level audio completely within the digital domain. Perhaps the most under-rated feature of the DAC+ DSP is the included operating system HiFiBerryOS. The OS offers out of the box web and mobile interfaces for easy remote control in addition to nice additional features like PEQ. In summary the DAC+ DSP posses the following qualities.

  • Web and mobile ui
  • Parametric EQ filters
  • Multi-source support
  • Parametric EQ
  • Command line tools

For those technically minded people that want every ounce of control, you can even go a step further and customize the DSP program on the board using the free Sigma Studio program offered from Analog Devices. Note the DAC+ DSP uses a ADAU1451 which is a perfectly capable SigmaDSP chip, however there is a limit of 10 total REW filters, which can be a bit limiting.

There’s a lot to write about the DAC+ DSP. The most important point though, is that for $75 and an RPI you can have a very capable streaming system.