Congratulations on having a top rate power delivery system. I don't think it would be beneficial to spend any more money there. It already is probably your strongest component.
I would recommend looking at the rest of your system. Overall it is strong and well balanced performance wise. So, it would be best to take you time and start at the beginning. Think about taking your system to a new level over time. Each upgrade will be significant... then at the end you get an extra reward for synergy.
I would begin with the speakers. You would want to bring those up to the next level first. That will likely take at least $6K or more. But I would take your time. Rethink what you want for the next level. Audition major speaker types.
Alternatively you might get an incremental bump by upgrading your streamer to the next level. I would look into an Aurender or higher end Lumin U2. Long-term look at the U2 purchase as the first step in your next level system as well.