What is your budget? And what would you like over and above what the Forza Noire gives you?
The high-end boutique cable makers that seem to get the online recommendations are Double Helix, Arctic, Norne and Forza. I’ve only bought from the first 2, and have the Double Helix Molecule Elite (OCC silver), Complement-C (OCC copper) and Arctic Cuprum (OCC copper).
I don’t have an Auteur but have adapters to allow all those cables to be used on my ZMF Verite/Aeolus, Focal Stellia and RAD-0, and I’ve noticed the same “sound improvements” on all my headphones vs stock.
The Molecule Elite is my personal favorite. It’s very thin and light, and doesn’t appear to change the sound vs the stock cable, other than sounding a little less warm, and a little more detailed, and it also appears to have more treble extension (i.e. it’s clearer and more extended but does not emphasize the treble). Silver cables have a reputation for brightness, but this is not a bright cable. It is less warm than the stock, but I don’t know if the stock cable is adding warmth, or if the Molecule Elite is removing it. I know a couple of forum members use this cable with the Focal Utopia and the bright version of the RAD-0, so I’m making an assumption that this cable is pretty neutral.
The Complement-C is pretty new and I’m still learning about it, so I can’t say much about it yet.
The Arctic Cuprum does not have the treble extension of the Molecule Elite and is slightly warmer than the Molecule Elite. It is less warm than stock and appears to extract more detail than stock. This was my go to cable before I got the Molecule Elite - it’s well made, drapes well and is not microphonic.
I may just be hearing the sonic properties of the underlying wire, i.e. regular copper (warm), OCC copper (more neutral, more detail), OCC silver (more neutral, more treble extension, more detail). I’m afraid I don’t know, but assuming that’s the case, then I’d say pick your favorite cable maker and order pure OCC copper or silver (or a mix, like you did with the Forza). Based on what I’ve read, pure un-plated cables have better sound than silver-plated copper (the Double Helix site has a good article on this) but I have no facts to back that up so YMMV.