It is great you have enjoyed your system and now know what it sounds like.
Your speakers are clearly the best component. Great choice… you have a lot of room to grow into them.
A bit of perspective. I am going to assume that over time you will want to upgrade everything to reach the full capability of your speakers. If you carfully choose your components for great sound quality that fit your taste it is not unusual for your speakers to represent around 35% of your overall cost of components (so ~15% for each: amp, preamp, DAC, and Streamer). So, that can help get some idea where over the long run you want to invest.
My first great system was constructed over many years. Once I had a system. Then I would choose a target component and upgrade with the intent of taking me “permanently out of the market”. Well, usually for ten years to the next upgrade cycle.
I would first upgrade your preamp. I would get the very best you can afford… used a great way… a Used Audio Research, VAC, Conrad Johnson will provide exceptional natural and detailed sound. Other great choices are Luxman, and Rogue.
Next the DAC critical in getting natural sound. A budget one that is really good for the money is the Schiit Yggdrasil. I would recommend a bit better one, but I am not familiar with that part of the market. But Yggdrasil would be a great upgrade.
Next… hard… a Quiet high quality streamer… then finally amp. Yes, streamers matter… one would think they don’t but the make a huge difference. My preference is Aurender… that is all they make and they are amazing sounding.
No hurry. You should get a big improvement in sound quality at each upgrade… so lots of rewards along the way. I started upgrading in the 70’s with components in th $200 - $300 range and have been upgrading in levels ever since and now have components in the $20K range and my system just gets better and better and more rewarding.
Also, make sure to really work on speaker placement and acoustical treatments. This can be free and make huge differences.