X-530 amp mod, harsh sound in mids

[50AE]

I'm not sure if this is the correct category to post this.

I decided to do a poor man's mod to improve the sound of my logitech X-530 a little. I disassembled the subwoofer and this is where I did the mods. I did the following things:

-I changed the junk 6800uf power decoupling cap with 3x panasonic FCs 2200uF
-I changed the front channel opamp with LM4562
-I changed the electrolytic coupling caps of the front channels and bypassed them with big film caps
-I also bypassed the power cap with a film one.

This is everything. A thing you won't like, I soldered a thru hole LM4562 to a SOIC place, I did it with small 1cm wires, which is not the best solution.

I get a very much different sound, after the burn in especially. Everything sounds better, but I have a problem. There's a section of the mids that is very harsh, I'm talking about the guitar solos and the violins. There's an unpleasant, harsh sound, I really can't describe it. Everything else sounds great.

The ugly sounding appears on rock and heavy metal songs, but not on eurodance.

Can you help me with this? Could it be the opamp itself? I bought it from eBay, maybe it is faulty?

[PreSapian]

i think the FC could be your problem. it's known to be a harsh sounding cap in any application.

[50AE]

Except the FC, I suspect values of components the opamp doesn't like, in the input or output. Is it possible?

[abraxalito]

If you post up a schematic and layout you might get more practical suggestions. My suspicions would rest with your new opamp not liking its power supply/decoupling/input RF interference. I have found LM4562 to be quite picky about those aspects - without proper attention to them, an NE5532 is easier to get a decent sound.