Will a high quality preamp really make a difference in sound?? Also speaker cable

My logic says if a pre is making your system sound better, then there's something wrong either upstream or downstream.

I'd rather have a good sounding amp and source with a passive pre.

I’m in the camp that everything matter within reason. If you have a Service Merchandise speaker with a VAC amp and a Nordost loom I think you not get the most out of the amp because the speakers are K-Mart.

If your room is less than perfect you will likely hear the difference a good pre can make but to me you're wasting money in fear of being beaten by the WAF stick.

You ultimately have to realize that you are playing at your own level and it needs to be fun.

Lots of responses but I agree with first one from knotscott. Preamp is signal processor and very much controls sound quality. I usually make my own speaker cables but you can actually find nice cables off Amazon at reasonable prices.

+1 @erik_squires 

+1 @gregrolka 

In the past I gave moderate praise to my preamps for the overall result of sound. More recently swapping a few preamps in/out with different Class A solid state and mono tube amplifiers both, I came to appreciate all over again what a nice preamp can really do for the enjoyment of the music. 

It would be a rare digital source with integrated analog volume control/pre that would best a quality active pre. Quality active pre provides dynamics, drive, harmonic development/natural timbre, source direct to amp and passives have inherent limitations here.