I'd like a portable headphone amp with mini jack input that has enough umph to drive at least a couple of monitoring headphones through a splitter. Obviously, since this is intended for production - dialogue monitoring - I don't want the amp coloring the sound in any way, just supplying enough amplification to allow more than one person to monitor through separate headphones. I would be using this with the DR-70D - since the recorder itself is $300, I really would prefer not to spend more than a $100 on a headphone amp... what would you recommend? TIA!