I want to change Opamp for front headphone output from stock NJM4556A to LM4562MA. Only problem is - looks like it's in series with another opamp - M33078. So there is no point changing only one, if they are in series. I think for sound quality improvement I need to change them both. 1)Is it ok to change them both with the same opamps? (NJM4556A and M33078 specs are very similar) 2)Can anyone tell what is M33078 purpose in this schematic? (Do I really need to replace it if I use headphone out only) I hope there is some kind of sound guru that knows this. Usually people are modding only soundcards, I haven't seen modded I/O panel, so no results in google. I have ordered only one opamp for now, to solder it in NJM4556A place. 1st pic is orginal, second is purchased Opamp and 3rd is already modded card.