T-Rex recordings are actually very good sounding recordings, Tony Visconti doing a pretty good job producing. However the later remasters are horribly brickwalled.
I haven’t found any HQP filter that can undo brickwalling, so I’d be surprised if Roon had the solution. Getting early masters with dynamic range intact or vinyl is your best bet for these albums.
It was always a suspicion that filters are not a clear solution. I was simply hopeful some folks had filter suggestions that would help thus saving me time.
I am not certain if the TRex I attempted to stream was remastered or not. Will be more discerning and look for original mixes and give it a try again. It is so hard contrasting the mixes of many of the newer artists with memories of my youth. The old stuff is simply “muddy” sounding too often. Dag it.