I know the Beats system is 2ohm but I have 4ohm Kenwood excelon 3.5s for the dash and 4ohm Fosgate 6.5s for front doors that I would like to use unless the power would be cut too low. Anyone have experience using 4 ohms with the Beats?
Hard to say. The reduction in power from the amp to the speakers is simple physics. If all else remained equal (you could magically convert a speaker from 2 to 4ohms) you'd simply get a reduction in speaker output. It wouldn't be half as loud because the power vs perceived loudness is not a linear relationship. For most people, a reduction in sound level by 10db approximates a halving of volume. That implies a 10-fold reduction in power. So for the same speaker with different impedance, the actual reduction in volume would probably be minimal. However, if the newer speakers are more efficient, that may be enough to overcome the loss in input power. Hard to say without having all the speaker and amp spec's.they will work but they will not be as loud ... power may even be cut in half ... they may sound better but with decreased volume you will be disappointed ....