OPPO-BDP103 vs. CD Transport

Currently, I listen to CD’s using my OPPO BDP-103 which is connected to my Denon AVR-2311CI via HDMI. Would there be any improvement in sound if I were to use an external CD transport connected to the AVR using a digital coax or optical input?

I preferred the Cambridge CXC over the 103 running into a Simaudio DAC. I noticed after that a few reviewers also preferred the CXC to the 103...and I do like the 103, currently using it in second system as a CD Player...and the CXC with a Denafrips Ares ll
Try the analog output of DBP-103 to AVR-2311CI, you might like the built-in DAC of 103 over the 2311.
Don't know anything about your Denon AVR, but I will add this. I owned the Oppo 103 previously and currently have the 203 which does have a better DAC onboard vs the 103. However my Emotiva ERC-4 clearly outperforms the 203 regardless if either are used as a transport to an external DAD, or as a stand alone player. The 203 does have the capability of playing SACD or DVD-Audio however but with CD its not even close when used as a transport or stand along player. The best performance comes from using an AES/EBU cable between the ERC-4 to my other DAC. I've yet to hear a coax or optical cable outperform a 110 ohm AES cable connection.