Lol - job done!

It was upgrading the resistors in the IQ-Audio DAC, as Dunc outlined, which have now been fitted with Z-Foils... All I can say is

It's a royal pain in the ass though, removing the existing surface-mount resistors, which are not much bigger than a pin head, and trying to solder-in standard sized ones (with tails) in their place, without at the same time lifting the track on the PCB, with the heat of the soldering iron!!

Not a job for the fainthearted, and certainly not something I'd recommend for anyone but the most able and confident at that type of task. Worth it, however, sonically? You betcha!

Marco.