A lot has happened since I wrote this…
Since I wrote this blog post, a lot has happened when it comes to audio on the Raspberry Pi. There are now cheap I2C audio DAC HATs that connects directly to the GPIO pins of the Raspberry Pi, and thus eliminates the need to go trough USB. This lowers the jitter that USB introduces and there are several cards to choose from.
I’ve tried two different cards, the HifiBerry DAC+ that uses the Texas Instruments PCM5122 DAC (PDF) and handles music all the way up to 24-bit 192kHz. I also tried the ESS Sabre based DAC DACBerry3+ from eBay. My personal favourite is the HifiBerry. To me it sounds better, but there are some quirks when it comes to set it up. You need to set the volume with alsamixer to 96% output otherwise you get distortion. There’s none of that problem with the DACBerry3+ because it doesn’t have software controllable volume settings.
The Raspberry Pi is a really small computer with an ARM 700Mhz processor in it. It has dual USB ports, Ethernet, HDMI and analog video out and sound. But the sound output is terrible. The audio is PWM driven to about 11-bits per sample, witch makes it practically useless as an audio playback unit. And all my plans for projects with the Rasp involves audio.