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

The most obvious advantage is that they can help some people get rich quick.

Best of all is that they won't need to present any evidence whatsoever of possible technical improvements over basic OFC. A fancy sleeve and ridiculously overkill plugs can help though.

Every time I have to unplug my IXOS interconnects and almost end up destroying the inputs on the back of my amp and CD player I congratulate myself for buying these 'wonderful' cables.