Unless you maximize SPL, one prudent strategy when you have an amplifier with 90watt RMS channels, is to get a speaker such that you can be sure you never have to send more than 60-70watts to it. I am not joking. First, the long power wires that run all the way to the trunk result in a voltage drop. Depending on the voltage it's seeing, your amplifier is now merely a 75-85 watt amp. Ok, let's assume you have a solid electrical system, enough to extract the 90watt RMS. The issue is that by definition, the moment you send 90watts to the speaker, amplifier THD goes up to 1% which is within the audible region. Granted, at this point, the distortion produced by the speaker itself is several times that number. I heard, by word of mouth, that Morel Maximo speakers have very good sensitivity (so you need to use less power to drive them) and they sound relatively good. The coaxial versions are pretty inexpensive. I also measured the voltage (playing a test tone) to see how many watts my hybrid audio imagine woofers are seeing. About 40-50watts each, which is great as I can be assured that they get an ultra clean signal from my 80watt amplifier. These are quite expensive though for a coaxial speaker.