Reply 2.
I have just the question for you. I am probably going to appeal to your rudimentary, common sense as one with an interest in audio, here because these questions are not specifically "engineering"questions. But you have the math let's say.

Any thoughts might help to settle an ongoing (and at times bitter) argument with the (my) wannabe whizz kid who may be very intuitive but non-communicative (so what's the use) and has very far to go before he is as handy as he likes to think he is (still practicing one handed eating with a utensil. But hey maybe he is well on his way to becoming a gorilla-man - of 70 kilos and standing 1.86 tall?). There is progress: he's hung in new doors at the house of the Bat from Hell. (After he scratched all the paint off my walls and doors). They allow for a nice fresh draught now (5 cm short). Schadefreude one of my guilty pleasures these days.

The set up:

How is the loudest sound achieved without "soundloss", which may be a bit of a big word in this set up? Settings on PC, using keys on keyboard (which is surely the same thing), turning up ADL or turning up Bose? So many buttons to turn...
Won't say who says what because if he turns out to be right I'll pretend it's me who was right: the last thing he needs is more hot air in his ego.
Let's ask the referee.

Headphones same question, but fewer knobs to choose from. Does one change volume levels on keyboard NEVER (or one will be slapped) touching amp setting?

Very critical point of debate: (sometimes used to back up argument above)
Which uses the most energy: the amplifier or the speaker when left on.
My favorite debate at 1 in the morning, after Whizz Kid has taken a 20 minute shower.

Clearly - even with PC off - they are on: light on ADL shows numpty this, Bose hums like crazy, and the plugs to the mains explain this, I get that. However, my audio guys (sigh), the little I can get out of them, declare everything can just be left on. Negligible costs, better for the equipment. Now, for a Naim Uniti maybe - still don't like the idea, but okay, it's on, night and day, they don't say what setting: front, or as is. Is muted radio the same as "switching it off" by choosing front... isn't it playing on in the quite background....that sounds like asking where do the people in televison go after you switch it off....but I am veering off equipment again. Back to the set up offered above.

What real difference (leaving my ever increasing hearing loss to one side) does a gold plug make in this humble set up?
And what IS the difference between one Grado Labs (SR225) and the staggered better versions (if you happen to know anything about headphones, a specialisation in and of itself). And why do my audio guys, you know the types, who specialise in record players (but laugh at cassette decks! Idiots, that's me stuck up memory lane - they took my old one away for repair and wrote it off entirely eventhough only one deck was broken, and I never saw it again; but no need for your disdain: they worship the tape reel as the most superior sound carrier ever invented and I presume that is also the kind of "tape" you have lying around ) these two then swear by this brand over all other brands. Hopefully for its unfangled qualities.

I tried asking the audio chaps. I am trying to learn all the time (as the only woman in the shop - can't be ageism they are both 50+ themselves as are most of their customers) but they would rather have teeth pulled than answer my stupid questions, which leads me at times to seriously suspect they don't really know as much as their laid-back hours, in-house dog, espresso machine and audio lounge (all very shabby to match the LP collection) would like to suggest. Or rather, it could be possible they are better at engineering I suppose than selling the stuff for domestic use. One of them has a daughter in a band....
Mabye they should put on their shop: men only. (Like you see hipster hairsalons do. Fair enough. We girls don't need be around all that vanity, but have we the right to good sound?)

I tried Googling. Result: hours, hours of afficcionados and 10.000 maniacs later I still don't have a clue.