Yeah I don't know. I've read brake bleeding threads top to bottom until i want to punch my own face.
Okay, the situation:
Bought my S6 3 months ago. Front pads were low, pedal was pretty nice though, firm and right up top. Had a set of Akebono ceramics in a box in the garage. Why not?
Install pads, easy. Nothing weird, I did not open any brake lines and come across anything odd. Simple pad swap. After the new pads the pedal was VERY soft, and would go 3/4 down. But braking was decent.It has improved some over a couple months, but not substantially.
So, over the last few days I've been bleeding a little each night. Do not have a power bleeder but I don't see how it would do anything that traditional bleeding won't~ other than making it easier.
Most recently today I used two lengths of clear vinyl tubing pressed onto each front bleeder and emptying back into the master cylinder. I used a 60ml syringe to pull all the air out of the tubing before opening the bleeders.
So, I sat in the car and pumped the brakes for 30-40 minutes, both with engine off and running. I ran the ABS output tests in VCDS also. I observed the fluid in the tubing- initially there were a couple tiny bubbles.
Pumping the brakes the reservoir level goes down, back up as the fluid returns. I pumped for 40 minutes.
There's NO air in the system. DOT4 fluid is 100% new now. And the pedal feel is slightly better, but barely. Braking power is great, but the pedal goes halfway down and is still soft.
The ABS in the S6 doesn't seem to support the bleeding function in adaptations.

What the hell am I missing?
Haven't bled the rears yet.. I will soon, but I don;t see how they factor in since pedal was initially great, swapped front brakes and it went to hell.
FWIW; did the SAME thing on my wifes car (also S6) and the pedal was a little soft for a couple weeks and then returned to feeling 'normal' .