A quality CD player or amplifier and the interconnect between them and
the loudspeakers will cause less distortion than 0,01 %. Variations in
frequency range or timing are also close to none.
On the other hand, a loudspeaker will cause up to 1% distortion,
with it's frequency range and timing being far from perfect.
Try a (blind) test:
Borrow a second sound system from a friend or hifi-shop,
and swap only the CD player and/or the amplifier, whilst using
the same speakers.
It is important that you:
a) use a record you play often and know well
b) play both sets on same volume
c) have a friend switch sets while your eyes are closed.
d) As a second test, now swap loudspeakers!
Chose your loudspeaker based on the type of music you like to hear.
Classical music for example requires best possible accuracy (linearity, transparency)
whilst sub-bass below 50 Hz only plays a minor role. On the other hand, if you like
to induldge in deep powerful bass, you will need to get big speakers with large
scale bass drivers.