Question about DTS on Integra DTR 8.2

I'm a beginner trying to get my first setup finished. I recently purchased an Integra DTR 8.2 receiver, and now have my Millenium DTS Decoder sitting unused on my rack. Do you think the Millenium decoder would work better than the one built into my Integra receiver. Also another quick questions, my Yamaha DVD-C920 has a built in dts decoder, as does my Integra DTR 8.2 How does the system decide which DTS Decoder to use? and which one of the three would be best?