2010 S6 issue

[S6owner]

Hi guys, new to Audi and the forum and looking for some help please!

Picked up a 2010 S6 from a non-Audi dealer just before Christmas, drove to relatives on Christmas Eve and didn't notice anything but then on Boxing Day noticed the engine (5.2 V10) sounded terrible upon start up (extremely loud tappity sound followed by noisy tappity sound once revs die down) and this noise does not subside. There was also a smell of burning when the engine was used 'vigorously' to high revs on the trip home. Considering this is a 40k car with full Audi service history this doesn't seem right! Anyone had one of these with a similar issue, or is it just the noise that engine makes?!?!

Have spoken to the dealer and they are happy to pick the car up to be looked at, but wondering if I'm best just getting my money back and avoiding future hassle?

Appreciate your thoughts,

Thanks

S6owner (maybe not for long!)