Speakers should be the first thing you base your system on and then eventually the last item of the upgrade. All speakers have an unique presentation. When you find that signature sound that you prefer, speakers become the foundation for which your stereo is built. At that point optimizing your system around those speakers to bring out as much of the reason you bought them should be the goal. Upgrading speakers when the rest of the components and the room aren't addressed is just masking the deficiencies but they still exist. I'm a great believer in if the first watt is crap then it's just amplified thru the whole system. That applies to your source which in my opinion is where you should focus. Simple things such as speaker placement and addressing reflective surfaces will make huge differences in the presentation. Have you considered a subwoofer? Properly integrated it adds bottom but also opens up midrange.
My .02¢
Upgrade speakers or DAC
Next upgrade is going to be either Front L/R speakers or streamer. Current speakers are Sonus Faber Olympica III, looking to upgrade to Il Cremonese. Streamer is Cambridge Audio Edge NQ looking to upgrade to dCS Rossini APEX.
Which upgrade will make the most significant improvement?