Literally my setup.The HD 800 (S) is great and worth it. But you don't need the RME for it, if you have a laptop, a balanced cable and a good dongle will do to drive it.
Laptop -> USB-C Female to USB-A Adapter -> USB-C Apple Dongle -> JDS O2 Amp -> HD800S. My electronics are 1/10th (around $120) the amount of my headphone, which honestly, is about how much you should look to spend on less important parts of your chain, the headphone being them most important.
Don't even need a balanced cable, SE will get the volume uncomfortably loud on High Gain even after EQ. Like max position is not painful, but would be uncomfortable to listen continuously.