Hi community! I own latest rMBP13 that is running Windows 8.1 via Bootcamp. In device manager the sound card is detected as Cirrus Logic CS4208 (AB 93), driver was installed automatically with Bootcamp setup. I've recently found while listening to music in WMP that the sound itself is poor. The volume is ok, but the quality of sound is like downsampled. I tried to listen the same mp3 in native MacOS 10.9.1 and everithing is good, sound is perfect, high tones are clearly pronounced. But in Windows there are almost no high tones.. Did you try to tweak sound or sound card driver in Bootcamp? Thanks in advance.