This was the home stereo setup with the big SB-G400 speakers. Input power rated at 200W, and I don't have any specs for power beyond that. Connected to that 70W receiver, you're looking at a hospital stay at anything past half volume.
Speaker manufacturers are notorious liars. Especially resi and automotive, where nobody's actually getting out voltmeters and doing the math. It's even worse than hard drive manufacturers who want to pretend that 1000000 bytes is a meg. Most of them advertise their "peak" rating as their watts, when what really matters is the Root Mean Square (RMS), or "continuous" rating.
Take, for example, those ElectroVoice 1122d speakers from my example. This is a really kickass pro-grade speaker. You can deafen an entire cafeteria full of rowdy middle schoolers into submission with 2 of these, easy, being driven by the appropriate amp.
Their peak wattage is 2400 watts. The RMS? 600 watts. So, the amp paired with them needs to be about 600w per channel. Often we go with the QSC CX-Q 2k4, which will get you about 700w per channel at 8 ohms (which is the impedence of these particular speakers), but man is it expensive. For this job, I went with a Dynacord L2800FD for about a third the price for the same wattage. Our DSP will have a peak limiter in its signal processing chain to make sure that too much power never reaches the amp for the speakers to get overdriven.
Numbnuts thought a Crestron AMP-X300 (at 150 watts per channel for almost the same cost as the Dynacord) would be enough, pushing through 18 gauge wire (which is fine if your speakers are only 20 feet away from your amp... these are not).