[Icecast] vorbis ogg vs. aac

[ZONA]

Hi folks:

this is my second question at this list and I wanted to mention that with
answers and guides I got from 2 persons last time, I got a quite low rate
stream in vorbis ogg, in about 5 minutes after reading what you wrote-
Thanks!
Well after that, I pointed my attention to the so called AAC, and after
tweaking a bit I got my AAC stream up and connected to Icecast serv.
I was a bit dissapointed about AAC, as I thought this was better
encoding/compression than OGG. I alpologise if I express my selv badly about
the technical detail, but the thing is that at low bitrates (lets say
between 20 and 80 kbps) OGG sounds a lot better than AAC.
As I still believe AAC is a really good one, maybe somebody can tell a
little about where or how I can get the best result with it.
(I can hear an anoying sound "behind" the good one, something like
metal/glass chorus at low rates with aac).

Thanks:

CC