I want to route my Scarlett 2i2 into the 1/4 inch jack of the KRKs and use the XLR inputs to connect wirh my S4 (using an adapter to fit the 1/4 inches of the S4).
Is that possible without damaging anything? Of course I would unplug the sound card that is not in use from the computer every time.
Should work, though you might run into an issue with one of the inputs over-riding the other. IE, if something is plugged into the XLR inputs, the KRK’s might ignore the signal from the 1/4". I don’t have KRK’s to know for sure, but other than this should be no issue.
Pretty much what Tarekith said. The connections will work no problem, it’s more about what happens when you have multiple inputs plugged in. I have KRK’s at home so I can test this and report back if you want. If I had to take a guess, if the KRK’s break any connections it would probably be RCA < 1/4" < XLR.
I doubt you’ll damage anything, as long as you don’t suddenly overdrive the speaker with too much signal.