The only Iissue you will have is when you split the RCA's with Y adapters you won't be able to turn on the LPF on the deck. The problem is the Mach 460 amps need a full range audio input. Your new sub amp needs bass frequencys. I hate to say it but you're better off returning that deck and getting one with 2 or 3 pairs of outputs. I am a MECP master certified car audio installer and have close to 10 years in the business. Just speaking from experience.