I've tried the CMI7838 with DiO2448 drivers a couple of weeks ago.
The cheap (€9,90) card didn't have digital i/o on the back but it had some pins on the board and with the chip datasheet I could make out which pin was which so made the digital i/o myself. I removed the mic input and the rear output with a soldering iron. In the backplate holes that came free that way, I mounted RCA's with leads to the appropriate pins.
I connected it to
my Mindprint DI-Port, installed the Dio2448 drivers running Windows 2000.
(I had to go back from XP to 2000 because according to the M-Audio site the digital out would not work with XP)
Playing songs in winamp came through nicely.
However running the ASIO setup for Cubase gave me all kinds of syncing and buffer problems. I could not run the checks or simulations without the whole thing freezing up unless I unticked 'full duplex'.
Well, the card is useless if it won't work full duplex.
I got fed up with it quickly, didn't want to put much more time in it while not sure if I would be able to get it to work at all, reinstalled XP and got me
a Delta 410. With €177,- in a totally different league but nada headaches is worth something.
YMMV, some may got it to work. I just didn't.