I can confirm this problem.
$ lspci | grep -i audio 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller 02:00.1 Audio device: ATI Technologies Inc HD48x0 audio
I, too, am using Ubuntu 9.04 amd64. I am seeing the exact same symptoms.
I can confirm this problem.
$ lspci | grep -i audio
00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller
02:00.1 Audio device: ATI Technologies Inc HD48x0 audio
I, too, am using Ubuntu 9.04 amd64. I am seeing the exact same symptoms.