Voice amplifiers

Choosing between expensive and quiet aerobics-style headset+waistband amp and cheap and noisy headset+waistband megaphone.

We’ve apparently got some gigs with the proto-outfit, so need to sort out some mobile voice amplification. The choice seems to be between

  1. Waistband voice amplifier + headset systems like those used by hoarse teachers, tour guides and aerobics teachers. They look a bit girly and my impression is that to get a decent one (like the WAP-7D) you need to spend at least a hundred quid and that you don’t get very much power (7W in this case).
  2. Megaphones with line-in from a headset. Megaphones are attention grabbing, noisy and cheap, and you often get a siren thrown in. So they’re cool, whatever happens to Obama‘s ratings. This guy uses one with a home made headset set-up for outside gigs, but (being pig ignorant about audio systems) I’m a bit concerned about whether the sound quality would be sufficient for singing as well as speaking. It’s also quite hard to find ones which don’t use press-to-talk pistol trigger grips.

Anyone know anything about this stuff? How much power would I actually need to cope with an outside crowd of say 100?