I was all set for for a Raspberry Pi Model 2 server experiment until somebody asked me if HRT's dSp would work with a Raspberry Pi. Good question. The dSp is a DAC: a Digital to Analog converter. It turns the zeros and ones that make up a digital audio file into the analog signal a pair of headphones or speakers pump into your ears. A good DAC is a critical step in making your audio files sound amazing, and some third-party DACs are much better than the ones built into your smartphone or even your PC.
That's when I remembered the cable hanging off the back of the amp and speakers in the warehouse. Nothing wrong with plugging that ⅛" jack from the amp directly into a phone or audio player, especially if it meant not using the cheap Bluetooth adapter that's usually plugged in there. But hey, what about turning the Pi 2 into a badass audio box that anybody on the network could use to stream their tune to the big speakers?
Suddenly, I had a project! A D-I-Y SONOS, if you will. (I love the SONOS system, we run three of 'em at home, I'm just not ready to buy one for the office speakers!)
And I have DAC issues. Or at least I could spare a DAC for a while. Within arms reach I've got a HeadRoom Micro DAC and Amp ($650) I used for headphone testing for several years, a Focusrite Scarlett 2i2 for recording podcasts, the AudioQuest DragonFly 1.2 ($150) that replaced the HeadRoom DAC for testing, along with the headphone jack on my laptop. I've also, as of late, received that HRT dSp for testing, and, because I was curious, ordered a $42 HiFiMeDIY Sabre USB DAC to see how it compared to the DragonFly, which, rumor has it, features a Saber DAC.
The differences from a the headphone jack on your PC and one of these USB DACs can be subtle. Beat-up earbuds that came with your phone, low quality streaming audio (or those 128 Kbps MP3s you got off your uncle's old laptop), the sound of the bus engine coming through your feet--all of these things make it difficult to hear the goodness that an excellent DAC can bring. But when you can actually hear it, it's like being in the room where the recording engineer placed the microphones. That's a good thing.
The audio built into the Raspberry Pi model 2 (or 1) is not that impressive. The hot ticket for serious Pi audio geeks is an i2s card that plugs into the pins on the Pi, but I figured USB DACs I already had (and could use for something other than a Pi) would have to work.