Something is missing

If there was an easy answer this wouldn’t be a hobby. It’s also why there’s such a thing as audio nervosa. Nobody said it was going to be easy. 😩

Are you experiencing the same sound with both sources? I would look at two things your phono amp, the one in your Rotel may not be that good, and as suggested above an external Dac for your Sony.  Possibly even look at replacing the Rotel.

I will second Jim Smiths excelent book. Its all about how to dial in your system to get the best out of what you already have. You might try moving your speakers closer together say about 8 feet and the same for your seating distance. That can improve dynamics and help minimize the effects of the room as well as keeping them away from the walls if posible.

I would agree on speaker position and seating position.
A lot of people make the mistake of thinking because it’s a large room they can space things out accordingly.
Not usually true.
Most people end up with speakers too far apart as everyone gets scared if they are just 6 or 7 feet apart.
IMHO just try reducing the speaker distance from each other and your distance from them and it just may surprise you.
I know Focal go overboard on recommending large distance between speakers but what's it going to hurt to try?
Cost?
Big fat zero.

The Jim Smith book is a good recommendation.   Should not be an issue with your gear if set up well.