Imac Sound Manager, inability to monitor Options

[29days]

I'm running Authentic Sound Studio by Innerloop, not that it really matters, my problem is that that the sound manager on my 400mhz g3 iMac will not let me hear myself while recording vocals. It cuts off the play through option when a external microphone is chosen, even if headphones are being used....I'm told by Innerloop that this is done by Apple to avoid feedback, but I'm getting really tired of being slowed by a computer that is supposed to be so "friendly" to creativity.

Does anyone have a solution ? Thanks.