Its sounds like possible stabilizer bar links also known as sway bar links. some links have a ball and socket style(more than likely yours are) not sure what theyll cost for an audi a easy test just grab a hold of the sway bar and shake it up and down you should feel any slack and might be able to re create the noise but youll have to be under the vehicle to really shake it . although its possible you need struts and/or mounts if its been a while or never done bouncing the car up and down with the hood open should show the strut bouncing if the mounts bad hope this helps good luck