I have 2 marine infinity kappa 62m speakers rated at 70w RMS and 220 max. I will hook them up to a 4 channel amp that supplies 55w RMS. Will this be enough power? Also, I want to add 2 6 x 9's to the other 2 channels, do I need to match the speaker sensitivity and recommended RMS power of the infinitys or will i be able to adjust the sound somehow when everything is hooked up. What's a good 6 x 9 to compliment the 6.5's.
Okay first, let me sort this out for you. You currently have a 4 Channel amplifier and want to hook up your Infinity Kappa 62M's
So on the first two channels of your 4 ch amp, hook up the 62ms.
Then, with your remaining two channels, you can just add 2 6x9's. One speaker per channel.
As for the bypass filters and what not, my recommendation is depending on how low of frequencies your amp can produce, you may want to set the high pass filter on your Coaxial speakers.
If you decide instead to add a sub wooffer and bridge the remaining 2 channels, I'll need to know whether or not your amp supports 2 ohm stability, or whether or not the channels are even bridgeable.
best case scenario is that your amp is bridgeable, in that case you just bridge the channels, and get a SVC 4 ohm sub. That keeps it simple.
Otherwise, I'll need to know what amp and what sub to give you other options. Or at least what amp you have so I may recommend a sub.