I have the one below, which lets each listener adjust volume slightly (nowhere near as much as if you were listening splitter-free). I also find the volume lower while splitting, compared to when not splitting, but it's OK. YMMV
[ame=http://www.amazon.com/Griffin-SmartShare-Headphone-Splitter-Individual/dp/B000EHCYBC/ref=dp_cp_ob_cps_title_1]Amazon.com: Griffin SmartShare Headphone Splitter with Individual Volume Control: Electronics[/ame]
Oh, I've tried three kinds of earbuds on the splitter and they all work fine, including the freebie earbuds that come with some iDevices. I've also tried some marshmallow-type ones that cost about 15 bucks and some noise-canceling ones that cost about 100 bucks.