Vibration through drivers seat

[NoggyRS4]

Hi all, new to the platform. I’ve had my RS4 for a few weeks now and have noticed a slight vibration in the drivers seat/footwell at around 40mph+, it doesn’t seem to change if I speed up or slow down. I originally thought possible wheel balancing, and need new rear tyres so had those replaced and still vibrates. When replacing the tyres I had a quick check over suspension arms and things, all seem okay, however the prop shaft does seem to me to have a slight bit play along with the centre bearing. Has anyone else experienced this issue? Any help would be appreciated. Thanks