so i went to best buy and bought a sony deckw ith blue tooth on sale for 99$ and it waas 52x4 but when i got home and opened it up no rca input
so im going to try to excahnge that but i worried because i bought it on sale so is there anyway i hook up a sub with out the rca inputs or is an adpater or anyhting im sure theres not but.. i might as well ask

 

Yes there is, and I am sure if you did a search you would find multiple posts where people have talked about wiring up subwoofers without an aftermarket headunit and just splicing into the speaker wires of the stock headunit (which is basically what you are doing)
So start searching.
Also, I am assuming since you don't have any RCA inputs in the back, you also do not have a blue remote turn on wire.
If this is the case you'll find that you need to find a power wire to tie into that is powered when the car is running, but not all the time.

By the way, at best buy, the product description always tells you if/and how many RCA inputs there are on the head unit.

 

yeh i noticed but i didnt know that decks dont come with rca wires i though it was a pretty stock thing to have on all decks found out the hard way

 

The deck will come with a blue remote wire even if it's a stocker, stock HUs have it too, it's for external accessories that need some way to signal accessories to turn on when the car's on, the deck is the most convenient way
As for the HU, return it, say you want to, if they ask why, say it didn't fit for a friend's car or something, keep the packaging as newish as possible
RCAs, don't get one with two sets, that will only be for front and rear speakers
a head unit with 3 sets will have front, rear and sub
yeah you can use front and rear for a sub but...eh...you won't be getting just sub frequencies, and even if you can use the LPF on your amp, you'll still get those higher frequencies
And don't go sony, especially a cheap head unit
buy an alpine or pioneer for some better quality, even along the same prices imo

 

yeh i went out and bought a jvc deck for 159 so hopefully it will sound good when i get the subs in
im getting them from my friend in 2 weeks got them with his car from my other bud and the subs have never been installed
im getting 2 12 inch energy subs in a bassworx box and a 6000 mtx amp i think its 1200w max

 

wow an aftermarket radio with bluetooth and no rcas. Certainly did not know some didnt have rcas.

 

yeh thats what i said when i got home i was super pissed off doesnt make anysense to me