@ddafoe, Since your RaspberyPi with the S/PDIF output running Roon is sounding great, I seen no reason to replace it. It is cost effective and is doing the job.
As you posted, your goal is to "try a few new things". I encourage you to try the RME DAC and also the Topping DAC. You need to hear these DAC's in your system to determine how they sound.
If possible, I suggest you give the Ayre CODEX DAC a listen. I temporarily used it in my main audio system and it sounded excellent. It gets warm so it does need ventilation. I suggest you use it balanced output to your amplifier since it will sound better with balanced outputs.
As you posted, your goal is to "try a few new things". I encourage you to try the RME DAC and also the Topping DAC. You need to hear these DAC's in your system to determine how they sound.
If possible, I suggest you give the Ayre CODEX DAC a listen. I temporarily used it in my main audio system and it sounded excellent. It gets warm so it does need ventilation. I suggest you use it balanced output to your amplifier since it will sound better with balanced outputs.