Reply to Connecting Kontrol S4 to Yamaha HS 80 M

I have purchased a new S4 and one yamaha HS 80 M for monitoring at home. To my surprise the input on the HS 80 M is either a MONO or a XLR and the S4 has stereo output with left and right.

Will an 2 RCA to MONO cable connector help me? Also, would this affect my sound quality?

Any advice will be much appreciated except for exhanging the HS 80 M for another one just because it has a different female port.