Strange noise coming from my 530

[JD2329]

I did a post last year on a strange noise coming from my E39 530i - a knocking clanking sound under load from a cold start that my mechanic and I put down to wear on the DMF flywheel (car had at the time done 78k). It would only be between 1-2k rpm and disappear after about 30 secs or so. It didn't get much, if any worse so I just drove the car and put up with it.
However the clutch has just been replaced and I naturally got the flywheel done at the same time.
Unfortunately the noise is still there...and it now happens when the engine is revved in netural, though still only between 1-2k rpm. At idle speed it's not there, and it doesn't happen every time the car is cold either. Really weird!
If anyone has experienced anything like this feedback would be most welcome...