Triode wrote: 
> Yes... I'm baffled by my posts here :), but its why I wanted to split
> this discussion from the thread on the Touch forum which is about
> functionality not subjective impressions of sound quality.
> 
> I can believe EDO impacts sounds quality, but didn't want to claim it
> initially exactly because of the direction this thread has taken....  I
> believe the main reason there is an impact for this for spdif is that
> turning off the internal dac means there is less audio related signal on
> the power rails (should be none!).  However this also leads discussion
> of cpu activity related noise which can be changed by whatever processes
> run which is the ongoing debate here.  In this second case I stand by
> the belief that unless the code which is executed to move audio packets
> around is changed in some way then I don't see it impacting sound
> quality.  Changing things which I can show does not impact the alsa
> settings or the code executed to copy samples around is extremely
> unlikely to impact sound quality (at best it impacts the content of
> un-accessed memory locations!)

I think it is sensible to attempt to tie in the possibility of sound
quality improvements to some verifiable factor ie the executed code.
However it happens to be the case that  most of the people who are most
interested in the subjective impact of these twaeks seem to be
ultra-subjectivists who believe that there is no truth beyond their
subjective impressions. It is obvious that *if* code changes produce an
impact on the sound of a competent dac connected to  the SBT then it
would be likely to be a very subtle effect. Anyone who is not a radical
subjectivist knows that there is a lot of "noise" in the subjective
response. I am afraid that the chances of picking out the signal (if it
exists) within this noise is very low. 

I think you should stick to your guns of at least insisting that
evidence is based on some change in the executed code, but I am afriad
that your constituents are not interested in any conceivable limit on
the concusiveness of their subjective impressions. I admire your courage
and patience, but I am afraid that a falling out along the lines
previously seen with TT 3.0 is inevitable if you propose to include any
element of objective rationality in your design agenda. 

Leaving that to one side, have you been able to make any measurements of
the S/PDIF out which could demonstrate and quantify the effect of the
EDO changes (and other mods). I was surprised to read on a PFM thread a
post from John Westlake saying that the S/PDIF out of the touch had very
high jitter (in the nanoseconds but obviously varying between the peak
to peak and the RMS figure.) I am fairly familiar with the J test which
is used to measure jitter in a dac,.but i am not sure how jitter (or
noise) is measured on the S/PDIF out. AFAIK such measurements are not
often published either by manufacturers professional modifiers or
reviwers. It strikes me that it would provide some middle ground in the
current "do tweaks make any difference to an external dac divide?" if it
could at least be shown that positive changes in the S/PDIF out could be
achieved.


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