TOPIC:

Hi. Due a hear trouble i need to set gain on right speakers and i note great diferences between input gain slice and output..

1.5db gain on input slice generate great improvement on soundstage and image but same on output gain isn't good as input way..... in fact, output gain are much more quieter,muddiest, and clearly blurrest.....

Any ideas about it?

Try 1.5dB attenuation on left channel output instead. That produces the same balance between left and right but requires 1.5dB increase in SHD level control to achieve same overall level. Attenuations are often wiser than gains.

In case it isn't obvious, an attenuation of 1.5dB is a gain of -1.5dB.

I can only guess that you may be suffering slight clipping when using gain at outputs although it isn't immediately obvious why gain at input wouldn't also cause the same effect.