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

Room acoustics matter a whole lot more. 

So you can call me a newbie, I joined to buy a McIntosh Power amp. Didn't really know this was a forum too. Already on Audiokarma. What do you need for speaker cables anyway? 10 gauge 105 strand tinned copper in a shielded 2 pair jacket? Agree with prof here, belden cables are just fine, but I make my own cables using only belden. I refuse to pay for a fancy jacket with somebody's name on it, besides I love the way everything sounds & that's all that matters.

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. 

It's all just wire. Get copper. Get a low gauge number (thick) connect it. All it has to do is get the electrical mojo to the drivers. It might be nice to tell you friends you have 25k in meteorite sourced. 99999999999 Homium nitrided virgin Ecuadorian copper fully framulated and encased in the foreskins of penguins,  but it's still just...wire.

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.