To upgrade, or not to upgrade, that is the question

+1 @ghdprentice any decent Ethernet cable is gonna cost $$$ for 70’, so I’d get something like a good TP Link extender and the DH Labs cable is likely a solid choice as well.  Also, I was recently made aware of these Ethernet filters that seem to provide meaningful benefits and at only $50 may well be worth a try while you’re at it.  Best of luck. 
https://www.dxengineering.com/parts/dxe-iso-plus-2

A mesh router with a ViaBlue to a nearby node from it.

fuzztone +1

It's un-possible to recommend anything with this limited information. If you want a path to upgrade, we need to know the system. 

Can you connect a computer in place of your streamer and run some tests?  Link speed, ping . . . 

Ethernet cables improving audio is a debated topic.  IMO, you are already wired, which is much better then wireless and 70 feet is not very far for Ethernet at the audio streaming speeds.  Other will disagree.  If the testing shows a good link speed, I would look at other aspects of your system to upgrade but without knowing more can't comment.