I am guessing the lower control arm or like you said the pad rubbing on the rotor. I had both
happen to me.
The lower control arm was more of a constant squeek. To fix this quick to save myself time before I changed them I bought a grease gun and injected grease into the lower control arm boot. Was good for 3 months.
The brake squeek was more metal on metal hight pitched noise. You can visually inspect the front rotor and you will see fresh metal rubbed off on the rotor if the brake is rubbing. When that was the case for me I used a long screwdriver and a hammer and slightly tapped on the screwdriver that I put against the pad and it moved it just enough to clear the lip it was hitting.
2000 A6 2.7 stage 3-
Stasis 6-speed trans
RS6 Intercoolers w/ RS4 encaps
5 bar FPR
JHM shift linkage upgrade <-- Great upgrade!!
034 track density motor/trans mounts
LWFW CM stage 4 clutch <--- crap crap crap!!!!! I switched to resurfaced FW and VAST clutch. So far so good!
APR Snub mount
B&M Short shifter
H&R sport springs/sway bars
stage 3 fueling/software by ?????
Things I need :
rear view mirrow (auto dim)