grinding noise

I have a 2010 Mercedes 300c 4matic sport. There is a grinding/ scratching noise coming from the front end that increases with speed. I’m not sure if it’s brakes, wheel bears or something worse.

Over the last few months I have been doing various maintenance tasks to my 2003 ML350 with 129,000 miles on it. The front differential was inspected and needed to have the bearings replaced. (I pulled it and took it to a repair shop). While apart I replaced front one brake caliper, both front...