Problem with audio distortion

I am a DJ and I have my own consolle at home too (other than the one @ radio). It is composed as:

Mixer: Pioneer DJM-400 with 2 Pioneer CDJ-100S (in)


DJM-400 -> Korg Kaoss Pad III (DSP)
Korg Kaoss Pad III -> Alesis airFX (DSP)
Alesis airFX -> Amplifier: Yamaha AX-596
Amplifier: Yamaha AX-596 -> Speakers: 2 x JBL SCS-178 SAT

When I bought all the primary stuff (mixer + CDJ), my audio store (known for not being honest) sold me a buck of cables. Some weeks ago, I was forced to replace them because they became too short. I then bought 6 x 5 m, Harmann cables (which I discovered they were “Made in China”, but only after opening the package).

After replacing the cables, the result was incredible:

  • The absorbed power increased a lot: before, if I had increased the volume knob of the mixer by 10% the difference was almost impossible to hear; now I even hear a gain of 5%

  • The effects of the 2 DSP’s increased a lot as the absorbed power

The negative side, however, was present: before, if I was mixing with the amplifier at 75% power, I heared about 80 dB; now I hear 80 dB at 35-40% ! But audio distortion increased a lot, too. And now I don’t know what to do! Is the audio distortion caused by the too-cheap cables ? But, if this is the solution, why the cheaper ones didn’t cause any ?

Help !!