kenglish said:
"Adding more db's" of amplifier gain is not going to help in most cases. Amplifier gain is a poor substitute for antenna gain. A good outdoor antenna is always better than an indoor antenna, although many people can get by with an indoor one.
Amplified antennas are going to add quite a bit more noise and distortion to your signal, and if you didn't have a good enough signal without the amp, it's not going to make a bad signal better.
And if you have one or more strong signals, they could overload the amp, or mix together (if there are two or more) and cause all kinds of havoc, possibly obliterating the weak signals.
Between the noise generated in the active devices in the amp, plus the possibility of overload caused by strong signals, I believe an amp should be used only when absolutely necessary. Many of these consumer-grade amps are poorly designed and use cheap devices. Their noise figures and intermod performance is usually not very good, especially at UHF.
Most urban areas don't need an amp.