I encountered strange problem with my Quantum 2 audio interface. I want to upgrade from stereo speaker setup to 5.1. my front two speakers (FL, FR) are connected to the MAIN OUT ports. I connected two surround speakers (RL, RR) into LINE OUT ports 3,4. When I go into my MIDI and Audio setup on my MAC and go into the speaker setup, where I can assign which speaker goes into which output of my audio interface, I try to change my surround left speaker to output 3, but i won't let me. I get an error message, that I cannot connect multiple speakers to the same output. I tried playing test sound and some music from the front speakers, and my rear speakers where playing also! I found out, that all Line Out ports are acting like MAIN OUT ports. I tried pluging the front speakers from the MAIN OUT into free LINE OUT slots, but the result is the same. It always plays together. And the setup cannot be completed, because my MAC is telling me, that I cannot assign two speakers to the same output. It doesn't matter where I connect which cable - it always deliver the same error message. Do you know what might cause this problem? Thank you.