Re: Stereo system
The amp is the limiting factor. The speakers determine the maximum load they can take based on the amp's output. The CD player should work at line level, so no, that will have no effect on the volume output. A good CD player can make a difference to subjective sound quality, but in this day and age CD Players are largely all good quality.
You may also need to check the impedence of the amp and speakers. 8 Ohm (denoted by the 'Omega' sign) is standard and most amps will drive 4-16 Ohm speakers. Older units tend to drive a smaller range, typically 4 or 8. I have an old pair of speakers that run at 4 Ohms, but most run at 8. Without going into too much detail, the wattage denotes the power of the 'drive' how much 'push' the amp gives and the impedence denotes the 'amount' being pushed (actually this is technically incorrect, the impedence is related to the current and is not the current itself). The best analogy is actually of a water pipe. The Wattage is the power which the water is pushed by and the impedence is the bore of the pipe, which is directly related to the amount of water that can be pushed through it.