could somebody help me out on the benefits of expensive phono and speaker cables?

IME, interconnects and power cables have more influence on sonics than speaker cables.

And selection of any cable depends on the component being used and the synergy with said component and system as a whole. Price may not be a factor.

For a balanced fully differential setup, interconnects have less affect on sonic signature. The difference in sound between low cost Belden and a high-priced cable may be negligible.
   For my modest system which is all tube single-ended, the cost of my cables is damn high. But that’s what works for me after years of auditions and upgrading.

Khiak
Do not waste your money on expensive cables. Me and my friends have spend thousands on expensive cables to our speakers, and there is this gentleman ‘b4icu’ from previous forum calculated the correct cable gauges for the amplifier we used. We bought 4 AWG copper wires from Amazon as recommended by him with spade and banana connectors and DIY the cables. For $200 between the 3 of us, we have 3 set of speakers cables. We are very happy with the DIY cables to our speakers.

>>>>>Everything is relative. It all depends on what you are comparing. Some cables ARE better than some others. Just because thick cables beat some other cable doesn’t necessary mean the reason is due to the cable thickness. There are lots of variables involved.

Here’s a real life example. At the Tenor/Rockport exhibit in the Tuscany Hotel in Las Vegas in 2001, best of show that year at CES, the system consisted of Rockport Hyperion speakers ($100,000) that were biamped with four Tenor tube amps ($100,000 total), and Jena Labs Pathfinder and Shunyata cables (estimated cost of all cables $10,000). Thus the percentage cost of cables in that system was only 5%. Actually less than that since I didn’t include all the isolation stands (5), the CD player and the Audiokarma break-in device that was used to break in all cables. Or the cost of the huge 40x50 room to put it all in. Of course $10,000 for cables is nothing to sneeze at for most working stiffs.

Aahhh CHOO!                            

@geoffkait  but you can substitute out all the fancy power cables and it wouldn’t make any difference whatsoever. Then you could substitute out the interconnects for  Belden  and it might sound slightly different, but it might actually be a hair better.