I have found that way to be the best for a couple reasons 1) most car stereos only have 2 output that are RCA which match the 2 AUX RCA's for the Rio, however for anyone else reading this I would not advise routing you stock stereo speaker wires into RCA's to run into the Rio. 2) buy routing it that way you are able to use the 4 RCA's on the Rio and the EQ to have more control over each of the 4 RCA outputs. Now as far as the best way well that all depends on your speaker set up. If you are using the built in amp in the head unit then you will lose that if you wire it up the way you were describing but if that doesnt matter to you then by all means go with that. I run a 5/ch PPI amp 4 mids & tweet and one sub (the sub gets an internal signal) so i just run the 4 RCA's from the Rio straight into it and it works great. there is no "right or wrong way" its all on your setup and your prefference