LET ME CLEAR SOMETHING UP!
ADA885/880 (yes, BOTH models) do NOT decode
1) Dolby Digital 5.1
2) THX
More specifically, both the 885 and 880 claim to be "Dolby Digital." This refers to Dolby Digital Surround, and NOT Dolby Digital 5.1. They are two completely different things.
In simple terms: Digital Surround < Digital 5.1. (go somewhere else for an explanation)
885 claims to be THX certified. OK. So they sound good to music enthusiasts, but again: they do NOT decode THX.
Q. What does this mean to you, the consumer? (had to throw that in ( ; )
A. For DVD movies, you are not getting true 5.1 or THX decoding. If you're only planning to play music, I'm sure they're pretty decent, however.
Q. So what do I use for cheap 5.1 decoding?
A. The cheapest alternatives are
1) the CSW DTT2500 speakers (5.1 decoding built in) and
2) a sound card/add-on that does 5.1 decoding for you (you'll have to attach speakers for each channel ... I do not know the specifics of this, however).
BOTTOM LINE: sucky sucky for movies, pretty decent for music.
[Calador]
(PS ... if you feel any of the info above is incorrect, let me know ( : )