i have 2 sets of GREAT Sennheiser headphones (one RS60 wireless and one HD-580 wired) that i'd like to have both play at the same time (for late-night movies in the dorm, etc). i have an Onkyo 595 and have everything hooked up to my computer as well. can i buy an RCA > standard 1/4" cable to output to both at the same time? (i dont want to have to buy a headphone amp) also, what output would i hook it into? i know if the headphones are in the jack on the front, speaker sound will not play. does that apply to other outputs as well? and does that force me to buy a splitter?