oshcar wrote: 
> "improve sound quality" -- i have no desire to argue this.
My potion Is I think you want avoid degradation rather than actively
"improve signal"


> dont know what LSB is

LSB = Least Significant Bits

To convert a 16 bit auidio sample to a 24 bit audio sample you add 8
zeroes od least significant bits.

It is the similar as converting Euros to Cents - it is the same value 
€1 = 100 cents  - 2 least significant digist have been added - no
change in value.

> dac chip accepts 16 bit -- dont why it needs more zeroes, or why it
> needs 16 more zeroes instead of 8 more zeroes.

It doesn't but if you have to perform an operation on 16 bit sample
(e.g. gain for volume adjust) and then any 16 bit operations usually
ends up with a 32 bit answer.   

Use ALSA "hw" devices and ALSA will not do any s/w conversions. 

ALSA is a general system which can handle many device capabiltiies so it
will do everything it can to avoid loss of quality in operations. This
means doing calculations/operations at highest resolution for as long as
possible and then dropping unusable  bits when passed to hardware (e.g.
32bit answer chopped to 16 bits to DAC).

ALSA can do software conversion when required (e.g. input 24 bit sample
but DAC only support 16 bit), volume control (add bits, volume adjust
and then truncate as required), resample (e.g. 96Khz to 44.1Khz if DAC
only support 44.1Khz). ALSA devices can also have other abilities such
as snoop, mixers etc.

SOX will do same job as ALSA because not all SB players have ALSA.  SOX
is most often used to resample - in LMS user can have better control of
resampling algorithm than letting ALSA resample.  Some users use SOX to
upsample.

So if have have a 16 bit input, use ALSA "hw" and have analogue/external
volume control - then within ALSA  16 bit sample will be changed to 24
or 32bit  by adding LSB zeroes in case there is processing and those
zeroes will be removed when output to DAC - if there was no
"processing", the 16 bit audio sample value will be unchanged from
input.


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