Thanks a ton for all the replies. To start with the member who asked if I'm a bot, I'm not. Saw the first two replies, wanted to see what others might add, and simply got busy and didn't log back in until now. But really do appreciate everyone.
For me, I'm not sure that it's the iPhone sounding as good as the Eversolo so much as the Eversolo sounding like the iPhone. I hear those who commented on the power supply and interconnect but the iPhone is on a very cheap RCA adapter so even if both have bad cables, the "better" one should sound better no? That said, I do have upgraded power supply and chord and WBC interconnects (I know they're not actually the world's best but shouldn't be the worst either).
I'm also not hearing the slightest difference between the different DAC settings. And I have tried both with the preamp turned up and on bypass to control volume from the amp.
I think from here I just need to go grab my Sonos and DacMagic from storage later in the week and see how they compare to the Eversolo and iPhone. (If that sounds better, maybe I return the Eversolo unit for another one or even stick with what I had until I eventually make some more significant changes in the system.) If there's no difference still, then I'll know the issue may be somewhere else. But that will be so odd. Maybe I'll even hop into a local store to test some different equipment and make sure my ears are working!
For what it's worth, @moonwatcher mentions reviewers calling the Eversolo thin sounding and I will say it sounds thinner than I remember my system sounding.