no, as long as the wattage of the speakers are compatible withe the head unit.e.g speakers 200 watts head unit below 200 ,or else you may blow speakers.
it is not practical to change the head unit on a RX8 The above answer is correct. There are many ways to make an after market head unit "fit" into the RX8, but you will probably lose the steering wheel stereo controls. You can connect aftermarket amplifiers to the stock head units speaker output and use aftermarket speakers. Get the MP3/CDROM addition for the stock CDROM head unit from a Mazda dealer.
No
"When you go to change the radio in a 2001 Jetta with a Monsoon system is ther anyway to keep the 6 disc CD changer and add a new head unit with subs and new speakers?"
Yes but you have to rewire the speakers.
Get a better head unit, an amp, better speakers.
Connect the positive (usually red), earth (usually black) and accessories (usually blue)into the new head unit making sure the positive is fused. Connect the speakers into the head unit and away you go.
The first thing to do is to check the connections at the back to the head unit that is on the dashboard if all the speakers are affected.
It could be a loose connection, it could be a problem with the speakers, or it could be a problem with the head unit.
Install a subwoofer, amp, aftermarket speakers, and a head unit. Possibly, the easiest way to get the best out of your car audio system is to upgrade the speakers.
Check for loose connections with a continuity meter. if both speakers cut out at the same time, it the wire harness on the back of your head unit or external amp (if installed) could be loose. If those are all fine, it's probably time for a new head unit or amp
you will have to pull the door panel off to access the speaker. the 95 millenia has a premium sound system so be careful. It may have 2 ohm speakers in there and if you replace them with 4 ohm speakers, you will get alot less power from the system and it will not sound as good. your best bet is to bypass the factory amp and wire the new speakers right to an aftermarket head unit.
go to a shop