20 foot long speaker cable: is it ok?

A number of members here have reported good results using speaker cables in the area of 20 to 25 feet.  Also, generally speaking, the higher the impedance of the speaker the less sensitive it will be to speaker cable effects.  I found an impedance curve for the JBL speakers you indicated you will be getting, which shows that their impedance doesn't go below 5.5 ohms at any frequency, and is significantly higher than that at most frequencies.  So that seems encouraging.

Best regards,
-- Al  

I have been using a 24 foot pair of 12 gauge speaker cables for 15 years with various systems in my living room.  Never ever had any problems.  

No big deal. Save your money for real improvements with your components and get some ordinary speaker wire. If you want to go crazy then get 12 gauge wire. The only thing you should avoid is 18 gauge lamp cord or thinner wire. Stranded cables are best because solid cables can be stiff and can cause contact issues and plug or connector strain.

Thanks @stereo5 and @shadorne and @almarg as always you 3 are extremely helpful ☺️

Will be ordering a pair of 20 foot 10g Belden pre terminated cables from BlueJeansCable soon.