of course that option was look previously, but first it's still $10 vs $150+$10, and then there's the case where the interface don't have it's proper space to be put. and also there is one more thing to turn off and on and is cumbersome for a TV solution. for my main system using in PC, a full dac+passive preamp are feed into the genelecs via balanced, it's just usecase priority to try for it. it's more like power plug availability, cable management, cost and ease of use.You can try your luck and get away from it. Also you buy Focusrite Scarlett Solo one of the budget audio interface with balance output, should not pay more than $150. It is cheaper than premium internal sound card.
If the hum issue happens, just get the dac or interface and wasted $10, if fit works, it just saves 1/3 of the total cost and a lot of trouble.
And when KRK did mention the proper 3.5->XLR cable pin config, I do believe they did do the design so that a normal 3.5->XLR would work flawlessly. their own app even need such adapter cable to work with noise generating and phone microphone mic for profile suggestion. so it seems like a high chance it won't go wrong and it didn't.
Can't say for other speakers though as we don't know the internal wiring behind each plug.
And most importantly, I don't need to drive a long way or wait for delivery service for cables, no time opportunity cost for that. not to say it's the best practice, but it won't do harm like blowing the speaker or the audio device out anyway so not a bad gamble either no?
Cheers