I've been basically shouting at artists in my booth to get them to respond or they crack the door open to really hear me so now I NEED a talkback system or I will lose my voice and patience. Right now, the headphones that go to the iso booth come from a Presonus HP4. The HP4 has only 1 stereo input so I cannot go into it. However, I thought that I could daisy chain another small 2 channel amp from the HP4 output (going to headphones) and add a cheap gooseneck mic for talkback. Channel 1 would basically be a thru and Channel 2 would be the talkback mic that I could throw the fader up on to talk and back down for silence. Any thoughts? I've only been thinking about this for a day or so. I know they make nice talkback systems but its not in my budget right now. I also thought about upgrading the HP4 to another unit with talkback included. Thanks!