One Super high end cable or mid level set?

I could see putting extra into speaker cables because they carry the signal from the amp to the speakers and that part needs to be done right (IMO) but not Valhalla and stock cables for IC.

That is too much difference.

Never use stock cables, at least buy something like cheaper Morrow or Blue Jean for IC and then get a good speaker cable.

My two cents...

Just for the sake of the "one great cable" argument...

If you have a brand you like a lot, I think it's OK to buy one pair now if you think you might be able to budget for an additional pair in the reasonably forseeable future. For example, I'm a big Kimber Select person (not trying to shill for their products; just providing an example).

I bought one pair of Select 1036's, then built the remaining cables in the system over the course of 18 months. For me, that was better over the long term than being somewhat stuck with mid-priced cables I wasn't really happy with.

I suppose the question is can an 'incredible' never to be upgraded single cable produce a more magical ( or even equal) sound

No. Stick with appropriate decent quality cables and save your money for improvements to gear and room acoustics.

two cents...

Performance and price do not necessarily go hand in hand when it comes to audio cabling, IMO.

There are a few one-man operations that provide excellent products that are competitive with cabling costing much, much more. Additionally, you can usually try their cables for 30-60 days before you commit to buy.

If your choice is to buy one expensive cable versus a complete set of lower cost, but excellent cables, I might recommend you at least try a complete set of the lower cost cables to hear what they do in your system.

I have recently had good experiences with Paul at Clear Day Cables, and Mike at Morrow Audio. There are other options as well that are discussed often in the threads.

As far as the "top tier", well known expensive brands of cables, I personally see no reason to buy new unless you're receiving a 50% discount or close to it. The opportunities to buy used examples are too common to have to pay anything approaching retail.

What Tvad said.