need help deciding on my audio build

RonRizz

I would still go with the 4 channel. Even if you do not use the 2 rear channels, as Big said, you have the opportunity to bridge them to a small sub in the future if you decide to go that route.
As far as the quality of the newer SS amps; Big has some bad information. These amps are great, and budget friendly as well. I have installed Many, many of them for friends and family, and not a single complaint yet. Rock solid, and put out their rated power specs.
The first amp I used in my Z was a new model SS reference amp. I have more SQ trophies than you have fingers and toes with that amp running both front stage and bridged to Sub.
I highly recommend SS amps to anyone that asks.
Don't just take my word for it.. Read some of the reviews online as well. And saving a couple $ shouldn't be an issue... Its a $110 amp for christs sake.

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P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals