40' speaker cable..will I loose sound quality?


Thinking of running a second set of B&W 805's off my Harman HK3475 to the far end of another room. It will be a distance of about 40'. Any advise as to expected diminished sound quality if any. Hate to purchase 80' of cable to find the sound is not up to par.
Thanks
fcmcargo
And I'd stay away from networked cables--they're as liable to exacerbate the problem as anything else

That is an absolutely incorrect statement.
I agree with Bob_Bundas on the networked cables. Also the larger gauge statement is correct.