i had a free time today, and i juz tested both RPI and CB2 audio quality
for RPI i used Raspbmc(XMBC) 3.5mm audio out(analogue)
for CB2 i used lubuntu with gnome player 3.5mm audio out(analogue)
for the music i used a flac file, one classical and the other dubstep @ 900kbps 44.1khz
for the speaker and in-earphone, i used a logitech pc speaker (nothing fancy) & a shure se425 (audiophile choice for earphone, beats is an overprice junk so dont bother asking me if i have one)
i wont use the software equaliser, nor tru the hardware control
i will also use the same low noise PSU.
(it will have the same level of everything hardware side)
what i find:
RPI DAC is horrible, very limited range of sound, low dynamic sound, bass sound is flat, low sound is is barely audible,mid high sound are also kinda flat IMO,vocals isnt clear and crips, on speaker.
worse with my earphone.
layman translation, bass is not good, vocals or treble details is horrible.
CB2 DAC tru line out (alsa codec, not hdmi), on speaker, it is okay, both low and high. nothing to celebrate about. layman, performance is mediocre like any basic laptop or mid range mobile phones.
with my earphone, the tiny detail that seperate a good DAC from the bad appears, the bass is a lil bit flat not warm(unlike the hifi device). low mid, and high sounds like a common mp3 files, so is the Vocals and treble.
layman term, its just like a basic pc or mid range mobile phones
i'm incline to choose CB over RPi due to better sounds, that is if you dont have a hifi speaker or headphones. RPI sound is just downright horible. the sound quality difference is noticeable even with a "normal" speaker/earphone.
without any additional usb DAC, RPI and CB isnt for an audiophile, or hifi equipment.
and if you are an audiophile, get a good usb DAC companion, low noise power suply, to go with your audio equipment. then both RPi and CB should not be a problem.
on a side note both device played the file smoothly without any skips.