Cable Length Optimization...Speaker vs Interconnect, etc.

Component placement constraints have me trying to decide the best compromise between amp to speaker and preamp to amp cabling. I'm on a limited budget, so probably looking at Blue Jean cables or similar (in cost). With a Freya+ I can use balanced or unbalanced outputs, but amp is unbalanced only, so have to use an interface at the amp end if I go balanced. 

Choices are

(1) pre to amp about 5 ft, amp to furthest speaker about 20 feet

(2) pre to amp about 18 feet, amp to speakers about 7 ft.

I lean toward option 1, but that isn't based on anything empirical. If option 2, even though it means adding an interface (Rolls MB15b, Rolls HE18, or similar), I think balanced might be the better pre to amp connection.

Thoughts? 

Paul