Question about Line Output of UR22MKII

Hi everyone
My Audio Interface arrives today but I don’t know how to connect it to my amplifier. I see 2 output ways, first one in the front, it has the headphone symbol, can I connect to the amplififer by using a 1/4’’ cable? by this way, I will need a 1/4’’ Male Plug to Dual 2 RCA Jack Cable
The second one in the back, I can see 2/R and 1/L, can I connect 1 line to amplifier or have to use both?