Welcome @Mick_Hicks_Hixy
Only you can answer if something is worth it, and for that you need a process to decide. First, I’m going to point you to a post I made years ago explaining a useful process. Yes, it was about a different product, but you get the idea.
That said, I’m somehat familiar with the Audeze LCD 2, and your other current equipment. The RME would give you more flexibility, but there are many ways to get EQ. What is it you think you are missing now?
My thinking is that both the headphones and the amp could be areas that might give you more bang for the buck in upgrades.
I’m also not sure - someone else would be a better source - if the LCD 2 responds well to EQ and if it has the capability you might need if you have to do a signficant boost in low end. A lot would depend on your listening volumes.
Please tell us more about your objectives here, the kind of music you like, and what you think are your present pain points or weak spots.