You just have to try it and see. I got very few signal with amplifier off on my previous RCA antenna. However, I get all channels without amplifier with Leaf. You just have to find a good location and direction for it. Out of 30 digital channels that I am getting with Leaf, I would say signal is sometimes weak for 2-3 of them. But it was weak even with my previous antenna. I will get a small amplifier for it to see whether it will stabilize my 2-3 weak channels. My amplifier is supposed to arrive tomorrow. Leaf is great! I placed it in one good location and get all channels I need without the need to change position of the antenna.
In my experience the Leaf worked great without an amp, however it's best to check on the coverage of your home before you'll know for sure. Go to http://www.antennaweb.org/ to see what type of channels may be available at your home and it will tell you if you need an amplifier.
What kind of amp are you referring to? could you link to one? And how does this amp work? From what I've read it will also amplify the noise too. You see I have one of these and get spotty reception inside. But when I place it just outside my patio door it preforms flawlessly 30 channels ( 23 crystal clear ). Inside 12 spotty channels. But it does work great