Hi Guys,
 
I recently changed the cable (to Roland's) that connects my guitar to audio interface because the old one began to lose its connection. Unexpectedly (at least for me) the sound got changed by a lot. I am fine with that but there is one particular preset that sounded amazingly and now it had lost its magic, sounding way too bright. 
 
Could anyone recommend any method / technique / plugin / EQ or something that would allow to get the old sound with the new cable? After all, it's the same guitar and the same preset :) Is there any hope or it's an extreme task impossible for a non-pro? BTW, how do pro-musicians solve the cable replacement issues?
 
Thank you!

Based on the limited info, if the sound is too bright, then the previous cable probably had a much higher capacitance/foot spec. Try using a coil cable, they have much higher capacitance/foot.

fix the old cable!
 
or try rolling off the high end at the beginning of your effect bin

brian brock
fix the old cable!

This is probably the best way to go.

If the amp sim has a presence control, try reducing presence rather than treble. A poor quality guitar lead not only rolls off treble but it reduces the signal received by whatever's attached to the non-guitar end of the cable. So there might be a need to reduce the sim's gain/distortion somewhat as well.

The "pros" handle this kind of thing by either picking leads that are good quality (which for guitar means one with a low self-capacitance and low handling noise) in the first place, or by sticking to the same or very similar cables. Sometimes a "poor" audio quality cable, such as a coiled one, might get picked precisely because it reduces treble and takes off a bit of gain - can be very useful when dealing with a Telecaster or Rickenbacker into a bright amp, but that's where sticking to the same make/model of cable becomes particularly critical.

I have done quite a bit of testing with guitar cables using amps no one can afford (original Trainwreck Rocket) and very nice guitars.  
 
Extremely low Cap cables are oddly enough, not the best sounding ones on the market.  
 
Evidence Audio Lyric HG is most pleasing cable to my ear across a variety of instruments and amps.  They are not a low cap cable, they don't even publish the spec.  
 
I've also done tests where I measured and cut cables to match total cap, and still heard differences.  (some argue cap is the only factor in cables, I disagree).  
 
The Lyric HG is absolutely not the most reliable cable though.  

EQ alone would probably do a lot, but hard to tell what the A/B comparison is.

A simple technique I use most is pan/loop a reference left or right and the guitar in the other speaker. If you are between them, you can tweak the guitar to match the reference.

There are also EQ matching plugins which will do similar but more precisely (provided you have the reference), but I am not sure of a good one that is free.