Order of importance of cables

AC power cables first IF you have dedicated/treated AC runs.

I have a dedicated run to my room (20A) feeding two MIT AC digital rectification outlets, then to a QB8 Quantum power strip and Echole AC cables - the best tweak and the best invested cash I have performed in my system.

"a chain is only as good as it's weakest link". It's probably safe to assume your ac power supply is poor-and since you haven't mentioned any I assume you have no power conditioning or isolation of digital. Without clean(er)ac power it's hard to evaluate the potential of your system. My suggestion is first buy conditioning. Next move would be the power cords to preamp and digital, hopefully with isolation value.. Then ic from digital to pre. Then ic from pre to amp. Only experimenting and listening will tell you the best bang for the investment.

1. Phono Cable
Nowhere in the whole chain is the signal so small and what is lost here can't be compensated

2. Speaker Cable
There is a interaction between Amp and Speaker Chassis to control the movements of the chassis

3. Hardware to Preamp
4. Preamp to Amp

when your RCA connectors from Preamp are cheap, coated .... be happy, this will save you a lot for cables, these inferior RCA plugs normally kill the majority of the incoming information (Studio Standard, copper=100, silver is 106, gold=90, brass is somewhere 60 and there is even worse out there in "High End"...)

5. Power Cord
Try to get one with top connectors (grip), Oyaide for example

Hello Rox.

I suggest cleaning up your power. An industrial isolation transformer makes a difference, but it growls, and should be outside the music room. Almarg has good advice too, but I would add that capacitance and dielectric absorption are your big enemies in line level cables, while inductance is your big enemy in speaker cables.

flg2001, according to your statement, AC cables are NOT important in apartment building because you can't install dedicated line for your music rig.