@stuartk this is a tricky one. Most of the cables will color the sound. I think another way of looking at it is what power cord would do the least amount of harm as far as sonic character of the amp is concerned and the overall synergy as well.
The sonic signature of your system is important. If you’re looking to round off the top end, or have a bit more emphasis on the midrange, get a bit more body and better bass…this could determine what cables to use.
I would suggest to borrow from the cable company and stick with major brands such as Audioquest, Nordost, Shunyata, Kimber.
In my system…warm and thicken things up but still maintain a degree of transparency, Audioquest Tornado and Hurricane. Nordost Norse 2 series cables (Heimdall 2 and Frey 2) excel at soundstage, precision and separation of instruments without making things bright. Shunyata was borderline bright and fatiguing. Kimber is about precision but in my experience with slight compromise in soundstage depth and width.
But…that’s in my system. I don’t have Hegel and my room is different. So these are purely my findings and nothing more.