line-in stays clean, mic signal processed

[raydar]

I recently freshly installed Ubuntu Studio Gutsy on a machine w/ Asus 
mobo, Intel onboard sound (fancy surround outputs etc. but I can't vouch 
for quality), and am running the realtime kernel.

Regular system sound has always worked fine, but I haven't been able to 
get Jack-based sound working right yet. I'll fire up the Jack Control 
and start Jack, then run Creox, Ardour, or both, and plug a guitar in 
(usu. through a pedal, sometimes straight in).

Through my speakers, I can hear the clean (or otherwise) line-in sound 
just fine, but no matter what I try in a mixer, Jack's connections and 
settings, Creox's settings, or Ardour's settings, I cannot get that 
line-in input processed--Creox doesn't mangle it and Ardour doesn't 
record it. But if I reach over and plug the input into the computer's 
mic input instead, it works, noisily--& there's an annoying noise-gatey 
effect, like mic voice activation or something, in Creox (not an 
intentional effect as far as I can tell), and whatever's causing that, I 
really I ought to be able to use line-in too.

This seems tantalizingly close to sounding like an audio port 
configuration change of some kind, but I'm just clueless enough not to 
know precisely where to prod in Linux. Does this sound like a symptom 
anyone else has had?

Jack settings, not that this will help if it's an audio hardware config 
thing, are as follows:
realtime
soft mode
priority = 0
frames/pd. = 1024
sample rate = 48000
periods/buffer = 3
port max = 256
timeout ms = 500
interface = default
dither = none
audio = duplex
input device = default
output device = default
input channels = 2
output channels = 2
input latency = 0
output latency = 0
(I'm showing latency of 64ms, but Jack goes xrun crazy on me if I don't 
select soft mode, and it's the best I've been able to do so far, 
unfortunately.)

Hardware wise, I'm showing, under High Definition Audio Controller,
ALC880 Analog ALSA Capture Device
ALC880 Analog ALSA Capture Device
HDA Intel ALSA Control Device
ALC880 Analog ALSA Playback Device
ALC880 Analog OSS Control Device
ALC880 Analog OSS PCM Device
ALC880 Analog OSS PCM Device

and in Creox's Jack settings, I'm showing
alsa_pcm:capture_1
alsa_pcm:capture_2
alsa_pcm:playback_1
alsa_pcm:playback_2
which are what show up as
capture_1
capture_2
playback_1
playback_2
in Jack's Connections window under alsa_pcm along with input & output 
entries for Creox.

So it seems like all the elements I'd expect are there.  I apologize if 
this is a hardware and not U.Studio issue; haven't heard a peep on the 
Ubuntu forums.

Thanks for any help!

--Ray