it would seem then that the phonostage is likely more of what contributes to the sonic output and all its qualities rather than the amp (assuming the pathway is a separate phonostage connected to the amp analog in)?
EVERY THING matters! Do not try to simplify this much. But to not confuse you more it is good to keep us at a bigger scale as components.
But for example REMEMBER that your CXA81 uses a "DAC chip" from a manufacturer ESS with model NR: ES9016K2M. That specific one component CHIP have its capabilities that it can do like for example:
"can handle up to 32-bit, 384kHz PCM data via I2S, DSD-11.2MHz data as well as mono mode"
But that is only a single black CHIP with several legs soldered to a PCB. That needs a certain range of voltage to power it. For that there is many components needed for this "simple" and isolated task among many others.
For example:
- It can be a coil of wires (transformators) or a switching power supply unit (PSU).
- It can be close to the chip or in another physical box on the outside (distance/shielding)
- It can vary the quality of the components.
As you see when ONLY looking at ONE thing that that chip need to be IMPLEMENTED to be working.
And for that one thing with the few examples listed above (there is many more).
THEY ALL MAKE A SONIC IMPACT.
That means that exactly the same CHIP in this case ES9016K2M sounds slightly different depending on (all the stuff around it) that is the implementation..
So your amplifier CXA81 on the digital input sounds not the same as another amplifier with the exact the same CHIP, because it is a different implementation. (Maybe you can argue that it has some common characteristics.)
That is number one mistake that is done that they are thinking that same CHIP in components is giving the same sound out.. ..no it doesn't.
Why am I saying all of that, is to point out that sonically everything matters.
But not to confuse you so much we can simplify and keep us in higher level view in forms of complete components.
On a higher level what matters little bit more than the other things? (If not mentioned that doesn't mean that it do not matter sonically):
- Stylus shape
- Cartridge
- Cartridge/TT setup (each of the set-up parameters can be done in several ways that may be more or less good way to do it.)
- Phono preamp
- Pre amp
- Power amplifier
- Speakers and setup
- Room
Do we get all those things right then we have in my opinion a good starting point.
But maybe my starting point is point is on a higher level than average Joe has.
TT setup is an art that I consider even some of the best is doing sub optimal procedures in my book.
Room there you need to have some understanding of physics and how boundaries interact. And where to place and types of treatment is needed.
There are so MANY variables that "contributes to the sonic output".
This is just a glimpse of those ;)
In essence the above also answer your second question:
This would also suggest the amps output from a digital rather than analog source should vary greatly as the digital processors including DAC are bypassed through the analog pathways? The sound character could be very different depending on the source.