Will be installing my second RF T1500bd-cp tuesday and need to know if i should use a spliter on my rca cable or use the pass thru on one of the amps?

Pass through on the amp. Avoid splitting RCAs if you can.

would yall recommend a line driver like the mx-3 with two amps?

Do you mean you want to bridge them to get 3000watts?

As long as you have a good hu you won't need one. At 4 amps I needed one

Pass through on the amp. Avoid splitting RCAs if you can.

Nothing wrong with a single y-splitter.

Pass through on the amp. Avoid splitting RCAs if you can.

Nothing wrong with a single y-splitter.

Is one splitter bettern than using pass thru?

Do you mean you want to bridge them to get 3000watts?

No im using one amp per sub in chambered box