I've had a pair of KRK rokit 5's since october (purchased the vintage gold set because they were on sale). Occasionally they don't want to work right off the bat and I have to wait a little bit for one of them to start working. Just a minute ago i was mid song and they both cut out. I know I have some issues with the audio jack on my computer (macbook pro) but I moved it around, shut the speakers off and turned them on and off, and adjusted the volume but they wouldn't turn back on until the felt like it

I have a long cable that is audio to RCA that i've been. I bought it at radio shack and thought it was a halfway decent quality. Any thoughts on why they do this? Is it the cable or is it an issues with the speakers?
Clean the terminals and if that fails, replace the cables.
Gilchrist custom
Yamaha SBG500
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100

Cathbard Amplification
My band