I don't know how I'll get the best possible sound with the OPPO and my receiver combination. I'm using a Denon3312ci for receiver. I currently own an OPPO bdp-93, hooked up via HDMI 1 only. (Ignore speakers for now.)
What I would like to know is, where would I gain the highest benefit in sound quality, using OPPO bpd-93, OPPO bdp-103 and OPPO bdp-105?
Would I get better SQ using the 93, or 103's Analog connections over the HDMI?
Would I get even better SQ using the 105's Analog connections over the 93 or 103's?
Or is the 105's Analog capability overkill for the Denon receiver?
I don't think the 105 will give you any benefit for straight sound, since your receiver doesn't have analog multi channel inputs. If you want some of the other features (headphone amp, optical inputs) that the 105 provides but the 103 doesn't, then that may be worth your while.
As far as sound, since you're talking HDMI sound, the 93 or 103 is your choice, I would think the reason to upgrade would be features, since the sound quality, while probably better may not blow away your 93. The features here are prompting me to upgrade, but for me it's easier since I'm upgrading from an 83. The ability to source other components through the 103 for video and sound, etc... all sound like what I want.
Soundwise though, I think your best bet is to audition one, compare it to your 93 and see if it's worth the upgrade.