I agree with "garbage in, garbage out." My experience though is that people often upgrade their amps to something expensive and fancy, keeping their shitty speakers, invite you over to have a listen, turn to you and grin saying something along the lines of "sounds great, right?"
The advise I was given is if you have a fixed budget of say €2000 for a stereo system, is to spend over 50% of that money on speakers. I believe the figure I was given was 70%, but I can't be sure. Anyway, it's my experience that this is correct. Just make sure you buy a quality budget amp & CD player, like the best NAD or Marantz available for that money (possibly a discounted but new slightly older model). Don't get carried too away with cables.