No, you’re not insane. Differences with digital equipment can be quite subtle. I find the recording used to hear differences can be important. A good solo piano recording often helps to reveal differences. And with a streamer, it may not be in the obvious parameters like tone or bass quantity, but in less obvious things like image solidity, stability, or noise floor. Sometimes these things can be heard in the space in between notes. If you have really busy music, they may not be apparent. If your room is not treated, they may not be apparent. Etc., etc…. For my needs, I decided a long time ago to look at features needed (e.g., inputs, outputs, storage, Roon ready, etc.) in these devices over alleged sonic advantages.
Right now I happen to have a $400 streamer I bought for other purposes. Using its SPDIF output with a $10 cable into my DAC sounds about the same as the main streamer, which is optically isolated, uses much more expensive cables, an outboard power supply, and isolation devices. There is a difference but it is very subtle.