I notice that Kardas have announced a connector design that creates a balanced RCA. Tip and sleeve on the central pin. Avoids massive XLR connectors and I assume is electrically compatible with single ended. I’m ambivalent about new connector designs, they usually die. Kardas claim it is an open design and available to all.
I guess it might gain some traction. But it isn’t as if Kardas have any market share right now. Topping could probably make or break the idea.
There's discussion on the forum and between us engineers.
The issue was that the connector is not available. The design isn't even consolidated.
The cables are potentially more expensive to manufacturer too.
Currently if we are going to save space for balanced ins and outs, we will use 6.35mm. It's already widely used, and only down side is that it is a bit deeper on the pcb. Other than that simply no reason to use balanced RCA for us. For even smaller devices 4.4mm is the way to go.
Things may change. If the connectors aren't up to the standard or either too expensive, it just won't happen. Or it may end up very good.