I found the percentages outlined by Robert Harley in this book to be a useful starting point.
https://www.amazon.com/Complete-Guide-High-End-Audio/dp/0978649362/ref=sr_1_1?crid=DCQU4I651FUI&...
And I learned a lot of other useful information as well.
https://www.amazon.com/Complete-Guide-High-End-Audio/dp/0978649362/ref=sr_1_1?crid=DCQU4I651FUI&...
And I learned a lot of other useful information as well.