RF William Hollender created this professional quality 24 bit 192kHz audio breakout board for Teensy 3.x, Raspberry Pi, and more:
Teensy Super Audio Board
Professional quality audio breakout board, mainly targeted towards Teensy 3.x and Raspberry Pi 2, but also should be compatible with any boards having an I2S and I2C interface broken out (FPGA boards with enough GPIO included).
Hollender described his motivation in this forum post:
PJRC Forum: 24 bit audio boards
I mentioned a while back in the Audio Library thread that I was interested in putting together a high quality (24 bit) audio board. I finally got to a point in my projects where a higher quality audio codec board would be helpful, so I dove in and put together 2 designs. One design uses a slightly better performance codec (a Cirrus Logic CS4270) than the SGTL5000, and the second uses the highest quality codec I could find that is easily hand solderable (the CS4272).
The KiCAD board project including libraries are on GitHub:
whollender has shared the board on OSH Park:
SuperAudioBoard
Hollender recorded this video about his project for the Hackaday Prize SemiFinals:
OSH Park 