the rme is a good dac, many features, great value for the $ - it has an upfront and center sound, fairly flat and narrow imaging
the soekris 1541 (predecessor to the current 2541, some believe it is slightly better, but that is a separate conversation) has, to my ear, in my system, a more dimensional, fleshed out sound, much more proper imaging and spatial properties
i think the rme is terrific for headphone listening but less capable in an in room system where the user is trying to use speakers and room acoustics to recreate a realistic stereo image
otoh, the soekris dacs have a headphone output but i have heard some say that it is not the last word in sound quality with harder to drive hp's... i am not so much a headphone guy so i cannot speak firsthand on this aspect