Hi folks. Recently purchased a Kenwood kdc-bt858u & biketronics retro radio adapter to go along with a pbr 300x2 and a pair or infinity kappas. I have been trying to read through this forum to get some tips on wiring this all together. Would it be wiser to use the 4v preamp outputs to the amplifier or cut the rca's off and wire the hu to the amp with the speaker wire. Also if using the RCA's do you have to run a remote wire to signal the amp to turn on? Thanks in advance for all of yall's help!

 

Using 2ch rca cable connect them to the front rca pre amp outputs from the headunit. then connect the other ends of the rca to the amp input. Then speaker output from the amp connect speaker from there to your new speakers. you will need to use a remote wire to turn on and off the amp. Connect that wire to the headunits remote wire. For the radio adapter wire harness, you wont need to use the high level speaker outputs. just tape them off since your using external power from the amplifier.

 

Thank ye!

 

Ditto!

 

ALWAYS use pre-outs (aka RCA's) as these will never send distorted or better said clipping signal, where speaker outputs will.
Now there are "some" exceptions where some amps we use "do not like" 2V pre-outs.
But 4V pre-outs or higher, ALWAYS use the RCA's if the amp got RCA inputs.

 

UNLESS, you are using the RF PBR300X4. For some reason, me and many others found that amp just likes hi level input. Nothing to do with the OP, just for anyone else reading or searched this.
Kris