I've looked at this fairly extensively now, the primary issue is the
ALSA driver, it does not support 192 (or 176). The S/PDIF data stream
comes directly out of the processor which contains a bunch of registers
which affect the output sample rate. Its not just an issue of sticking
"192" in  a register. There are a whole pile of parameters which have
to be set correctly in order for it to work. Example are: clock select,
prescaling, buffer size, interrupt frequency, a whole bunch of others I
don't remember. Last time I looked it was not obvious what some of
these paramters needed to be. It would take some time to figure all
that out and do a bunch of trials to get that working. 

Then there is distribution, this is code that is compiled into the
kernel, not something you can just change a number, its pretty much
something you would have to convince logitech to change, they have not
been hot on kernel changes at this point. So even if someone comes up
with the code change for the ALSA driver, you would have to convince
logitech to make that change. 

So yes it is theoretically possible, but it will take a significant
amount of work to implement and logitech has to bless it and include it
in the firmware. The probability of this happening is pretty low, you
would have to get an awful lot of support for this to convince logitech
its something that needs to be done. 

There is another fly in the ointment at this point, the current crop of
TOSLINK receivers are NOT fast enough to reliably support 192, so very
few if any DACs support 192 over TOSLINK. There is no way for the Touch
to know whether you are connecting via coax or optical. If the driver
gets updated to 192, and you use optical connection to the DAC, then
you won't won't get sound at all, no message from the Touch, it's
happily sending 192 over the link but the DAC can't read it. Logitech
is a bit reluctant to put out a system that works this way. Many of the
DAC manufacturers that support 192 go to great lengths to market their
DACs as being 192 capable, but don't make clear that it won't do that
over TOSLINK. Logitech would then have to deal with all the upset
poeple who bought a 192 DAC, and the Touch says it supports 192, but
when they hook them up it doesn't work. They are a little reluctant to
be in that situation. 

John S.


-- 
JohnSwenson
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