But I've read on the interenet that in order to take full advantage of the RTI12's, you need to run 300 watts to each tower. I'm not sure if 80 watts would be enough to power all the speakers in the tower.
Also, what does efficiency mean? I've always seen speakers efficiency rating but what does it actually mean?
Let's dig into this a little. A 90 db efficiency rating means that the speakers will play a 1000hz test tone at 90db (loud, by the way) at a listening distance of 1 meter with 1 watt of amplifier power. That's 1 watt, not 100 watts. Yes, as you move further from the speaker than 1 meter the dB level will decrease but not by much in a room in your home. For each 3 db of increase in sound pressure level, you need to double the amplifier power. So 93 db would require 2 watts, 96 db would require 4 watts, 99 db would require ear plugs for me. You get the idea.
Anybody that tells you you need 300 watts to drive a 90dB efficient speaker in a home environment simply doesn't have a clue. You shouldn't take any advice from such a person.
Now let's get back to our 4 watts. Just in case, let's provide for 10 times the available power to handle any potential peaks beyond the steady state test tone. That would double the the volume, by the way - earplugs for all of us if it were steady state. Now we are at 40 watts. There simply isn't any way to use more watts than that unless we are in a very large venue (a long way away from the speakers) or unless we really want to damage our hearing. So is 80 watts enough? Obviously. More than enough.
Audiophiles have always had unrealistic expectations about necessary amplifier power. I don't know why. I think it comes from the manufacturers who have been in a "power" struggle since the early days of audio. 50 years ago 15 watts per channel was a typical amplifier power rating. As you can tell, it handled most home audio requirements just fine. Today we seem to think we can't get by with less than 200 watts per channel in home audio but I'm here to tell you that is just plain nonsense. Those who believe that need to connect a watt meter to a speaker system and monitor for a while. It will be an eye opener for most audio nuts.
If you want to buy a more powerful amplifer, help yourself. It certainly won't hurt anything. But do it because you want it, not because you think you need it.
Best of luck to you.