On 2008-09-08, Ross Herbert wrote:
:Ross...good idea but not an option because we want the sound heard by
:all...approximately 15 people at a time. We already have and use dual & triple
:stethoscopes but they mean the task has to be repeated over and over whereas if
:we could just broadcast for all to hear at once...presto!
I see. Looks to me like your best and easiest solution is the medical grade
isolation transformer then.

Why not just use active speakers which are powered by batteries?