Which Preamp "internals" would you choose? Based on picture only

Every ROHS compliant solder I’ve ever ’heard’ sounds very subtly ’hard’.

I even know of one company that will not sell into ROHS compliant territory..as the ’no lead’..... solder changes sonic signatures too much for their liking.

It is a problem that RHOS complaint region manufacturers have to pretend ---does not exist. Or manufacturers that have turned into the ROHS wind and become wholly ROHS complaint.

It is a minor, but notable and pervasive change in sound qualities that are available at a fundamental level. It’s a subtle but near irreversible step backward in the realm of sound quality. Something that makes pinnacles previously known--into being unobtainable. the ’hard’ bit in the sound quality is also slightly, subtly ’hazy’, part of what it is doing at the fundamental levels.

Further, I know of one engineer at a well known major solder manufacturer, who says that ’there are no lead free eutectic solders’. that none of them (eutectic ROHS solders) actually exist, no matter what the claims may be.

Thus another group that is fundamental to this situation, saying that something ’is’, when it is not.

For the audio world’s obtainable pinnacles, ROHS is a subtle but actual step backward in obtainable sound qualities. For the junk end of the spectrum of tv's electronics, blurays, etc...who cares. No big deal. For extremes, the kind we spend the money to try and get to, it is a soon to be pervasive (everywhere) issue, a fundamental issue.

No one wants to speak about this.

Which amp are you referring to?

There is so much variation in components, layout, parts selection, and so on, that this subtlety can be swamped, if you don't know what to listen for.

What it takes to really hear it and know it... is to complete a new piece of gear with about 3 of the top ROHS complaint solders and then do the same piece again, with leaded solders, the ones considered 'best' in the world of audio. Then burn in, and try the 5-6 items individually...wih the only differences being the solder, in a-b/etc aural testing.

Then you'll learn to recognize what ROHS does. A subtle but pervasive downturn in sonic qualities available, in my experience and that of some others who are willing to do the involved level of testing, and actually make mention of it.

It's one of those things that no one wants to talk about.

@teo_audio - that is all very interesting and education about ROHS solder, but what does it have to do with the OP's question about comparing 4 different preamp internal pictures?

He must be accidentally posting in wrong forum. I do know more about solder than I ever have