Do expensive cables/wires REALLY make a difference

Yes. expensive or not, cables do make a difference. 1st replace your power cords. Live with those for a period of time then work on your interconnects and speaker cables.
Happy Listening!

im fairly new to the hifi worldbut im confused about something.my local hifi dealer/repairman advised me NOT to use a power/line conditioner to plug my gear into,telling me to just use a power strip saying the previous can actually make my system not sound as good as it could/should.is this true?? One more question i have is if the stock power cables are replaced on amps,cd players,etc will it make a difference if you do use a power/line conditioner?? thank you for any info.

Cwby8115, Now you've opened a can of worms re. power conditioners.
Check the archives, the comments and theories are endless.

The first question is how good is the AC in ur house now...is it steady 110/120 Volts, does ur neighborhood have brown-outs? Then there is the question of how clean/dirty the AC line is. I believe you should start by having the system on it's own dedicated line and breaker.

01-08-13: Buconero117
Double blind tests conducted by many of our 'authorities' over the last fifty years prove 'expensive' doesn't make the difference

01-08-13: Schipo
Why get out of the hobby? Picking and telling the difference between cables in a double blind test was no better then chance.

01-08-13: Sebrof
Buconeroll, can you link to these or somehow reference them. I see a lot of mentions about these tests but can never ever find any information on them. So I go on believeing they never happened.
TIA

Why does everybody keep talking about stuff that never happened?

I think Larry Greenhill did a double blind test between zip cord and Monster Cable in Stereo Review in the mid 70's...