RCA vs Digital connection

Using the RCA cables to go digital will give a slightly better signal, but many DJs will use digital so as to free up the RCA inputs for other gear (Turntables or other CDjs).  If you are not using anything digital in the signal chain then RCA would be fine, but make sure you select Digital or line/CDJ on the appropriate channels.  If you are recording, use digital, if playing through a normal size sound system, RCA will be fine.

Thanks for the reply Jay! Ok got it.. Would it still be okay to go digital if I'm djing in a larger venue?

Good question, My main Rekordbox consists of MP3 at 320. When I use RCA vs Digital I feel I have better sound quality - I have a 900NXS2.

But I also have an 80's collection in FLAC and use Digital for that when I do 80's parties. I feel the sound is better....

If you use the digital output from your CDJ's connecting them to the mixer you will cut out two A/D conversions of the signal which will result in a better quality sound. The digital path allows for only one conversion, in the output stage of the mixer. Always use the digital output from the CDJ's when possible.

Whether or not you're recording the mix from the mixer has no bearing on whether the connection between the CDJ and the digital mixer should be in digital.  Use the SPDIFs.  It not only prevents another conversion/re-conversion stage (DA to AD) and maximizes sound quality (rather than dropping sound quality a peg or two from its original baseline), but it prevents the possibility of input stage clipping and makes the input channel meters sort of accurate on the digital Pioneer DJMs, which they aren't with analog inputs since the meters are post-AD conversion and affected by the digital domain EQs -- hence the reason Pioneer added "clip" indicators recently on the newest models.  FWI, the floating point in the DSP being unclippable does not apply to the DJM digital output or any of the analog outputs, which become fixed point.