I'm not going for 100% accuracy, but directionality. Pedants need not apply, but if I've got anything grossly incorrect, please chime in.
So my questions are this. If I leave my magni in low gain, does that correlate to the amp staying in class A longer (as it relates to the volume pot position) compared to high gain?
First, I don’t know if Magni 3 operates in class A at any wattage. But let's assume for fun it's an A/B amp. Then yes… that would be true. (I have no idea re: the topology or configuration of the Magni, and I'm too lazy to look)
And then what I'm really trying to figure out is how this applies to the pre amp portion. Am I correct in assuming the signal strength is like a snowball rolling downhill? The longer it rolls the larger it gets. If you feed an amp (class a/ab/d) a strong signal (voltage) from a good source, does more of that originating signal make its way to the speakers then if a weak signal is massively amplifed once it hits the amplification circuit?
Not really, no, but I see where you’re going with that thought.
Is this an ideal way to get a high quality signal through an amplifer? The stronger/better the signal the less the amplifer needs to do?
Not really…
The
work an amp does is only related to the output. If you keep the volume from the speakers the same (output the same), the amp is working no more or less “hard”.
You do want to feed an amp the "best" signal you can. The only thing that matters is what does the best job of maintaining it along the way while amplifying it (or attenuating it). If you never wanted to change the volume, then by definition, the "best" signal would come straight from the Modi to your amp. If your Modi had enough juice (or speakers were efficient enough) then the best signal would be straight from the Modi to your speakers. If that boggles your mind, then pause here.
The more the amp needs to work the more the signal is changed, for good or for bad. If an amp has a stronger signal put into it, it can stay in it's peak linearity zone longer?
I tried to understand what you meant by this. If you're thinking that certain amps may sound better within a certain range of output wattages (the amount of work they're doing) then yes that's usually true. You control that with the volume you listen to your music and choosing speakers appropriate to your amp's rated output at certain impedances. Better yet, IMO, pick an amp appropriate to your favorite speakers. (See the posts related to the new Aegir as an example of why people are talking about high-sensitivity speakers and asking about low impedances).
By definition, the only thing you want an amp to change is the amplitude. That’s what an amplifier does. You’ve maybe heard the saying that the best amp is a wire with gain. As for peak linearity zone… most amps are very linear. They may add other noise/distortion, but most are extremely linear in their operating zones. Don't worry about input voltage (within reason) affecting the linearity of your amp. If you're hearing a difference in SQ, it's
probably not because of that.
Will I get better sound through my existing aged 2 ch system if I run mimby into magni into my amp?
I’m doubtful, but maybe. Give it a shot. What are you using as your current pre-amp that you’d be subbing in the Magni for? Be careful! Start with the Magni on a low volume setting on low gain. You probably won't fry anything, but if you break something, then you've learned something.
I joke a lot on this forum and am usually reluctant to provide advice, but if you do try it out - I'd VERY strongly advise not switching from low to high gain while listening to your 2ch system except at low, low, low listening levels. Switching from 6dB to 17dB (I'm assuming the gain switch also effects the pre-outs) of gain while you're already jamming out, could do some permanent damage depending on your gear, and I'd feel bad. You might find yourself replacing speaker drivers and other stuff. If you're on low gain with the volume maxed, and it's still not loud enough for you, reduce the volume all the way, THEN switch to high gain.