I would suggest toning down the requirements a little bit.
To start with, there isn't much point to adding more bits
above 24 per sample. The reason for this, is they are
"lost in the noise floor" of the sound card. So, you might see
16, 18, or 24 bits for playback, but doing more than that is
pointless. The extra bits would wiggle, but the noise in the
audio channel would smother their influence.
And when posting to an audiophile USENET group, I'd refrain
from using any numbers in your initial post, because it will
annoy respondents. You could say something like "I was using a
Creative X-Fi Elite Pro, and it was lacking something". Explain
you want good music playback, and not game support. That
would give the respondents a chance to explain the things
they think are important in a sound card. If they see you
asking for "48 bits", they're going to skip over your post
and not reply.
M-audio is an example of a company that makes sound cards,
with less of an emphasis on gaming. While the following card
does support EAX 1 and EAX 2, my $7 card does that too. So they're
providing a basic level of support for games. There is more
emphasis on sound reproduction here.
http://www.firingsquad.com/hardware/m-audio_revolution_7.1_review/def...
You can also find customer reviews on Newegg for some of these
things, and the usual complaints. For example, not all OSes
would have the best driver support. If you're on WinXP 32bit,
that is probably covered OK. This set of reviews is for the
Revolution 5.1.
http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16829121122
M-audio makes PCI cards, but they also make rackmount Firewire
boxes. The difference there, is the ADC and DAC are in a separate
box, shielded from some of the noise from the PC. But to see how
much of an impact that makes, compare the noise floor specs for
the PCI cards versus the Firewire boxes. (Specs are listed for each
product, on the m-audio.com site.) The Firewire box also
offers more channels, and the ability to patch things in, that
might be more physically challenging with a PCI solution.
This particular box is limited to 192KHz playback to two
channels (stereo).
http://www.m-audio.com/products/en_us/FireWire410-main.html
You can have a quick browse here, to see some of the things they
make, and the prices.
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=50001793+...
So I wouldn't really expect to see much more than the 24 bit,
192KHz sampling rate you've currently got, but perhaps slightly
better implementations of that (better DAC or ADC or better
opamps etc).
To see the current technical limitations (noise floor limiting
what can profitably be done with the number of bits), try the
Analog Devices web site. The second link, for example, shows
audio bandwidth capture devices being limited at 24 bits capture.
So if the companies who make components like this, stop at 24 bits,
then it is going to be difficult for a sound card company to go
past that point. There are more specialized companies than this,
and I'm not attempting to do a market survey here, just illustrate
the speed versus bit rate versus noise floor issue.
http://www.analog.com/en/subCat/0,2...om/IST/SelectionTable/?selection_table_id=207
Paul
