You will get great sound from either using HDMI or the analog outs. However when using HDMI you are using the receivers bass management while with the analog outs you will be using the OPPO bass management.
The OPPO also has a fixed crossover of 80 while your HK will have a flexible crossover setting. Setting up the system using the analog outs is a bit more difficult and takes more time. The analog section is great for people that do not have an HDMI receiver but if you can pass HDMI it is preferred.
I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.