Must we use a mixing console after I/O?

Hi,

I was told we can't directly connect the IO(like 192 IO, omni IO...) to speakers, must thru a mixer... Is this true? Why? I really feel there's no need for me to have a mixer in my room... and How can I connect 192 analogue output to speaker, as the output on the back of 192 are not XLR or TRS...



Thanks!