Wow, that Asus Xonar HDAV looks like a good
find! The “Deluxe” version has good
power supply sections and looks to have good TCXO clocks. However, it appears that Asus only developed
drivers up to Windows 8 for this. (Windows 8.1
and 10 are not supported). The card was
discontinued a while ago. If you are
running Windows 10, the ST / STX / STX II are still supported with new drivers.
I read that article “Why Audio formats
above 16/44.1 don’t matter”. This has
been a controversial subject in the industry.
I will say that several years ago I did some testing. I took a 16/44.1 version of a song (CD audio)
and compared it with a 24/48 version of the same song from the same album
through my Krell HTS 7.1 processor. I
did definitely hear a difference. The CD
version with lower bit depth / bit rate sounded a bit messier. The 24/48 had a cleaner and more solid sound
and the resolution of individual instruments was definitely better. I will say that it needs equipment with very
high resolution. Otherwise, you probably
will not notice any differences.
I also have done some testing recently
comparing both 2-chanel PCM audio and 5.1 DD/DTS through different transfer
mechanisms.
When playing a movie, the Dolby Digital /
DTS is an encoded bitstream that is sent to the processor through a digital
cable such as COAX, optical or HDMI. The
processor will then decode the data and split the data into individual PCM
channels (such as 5.1 channels). It will
then clock the individual PCM words at the proper sampling rate (such as 48khz)
and then sends it to the DAC chip. So,
ultimately, there isn’t much difference between COAX/optical and HDMI for this
transfer. It’s really just data at this
point. However, if you want to be able
to decode and play the bluray hi-res audio formats (Dolby TrueHD / DTS-HD MA)
you must do this through an HDMI connection (licensing restricts any
player/software from transmitting this through old spdif coax/optical). If you do use a COAX/optical, the player will
automatically down-convert to old compressed DD/DTS formats. There is a difference in sound quality
here. The compressed stuff sounds very
rough in comparison. The hi-res
TrueHD/DTS-MA will have a smoother and more realistic sound.
When playing 2-channel PCM audio, such as
CD or 24/96 hi-res, the player/transport will take the raw PCM data and clock
it at the proper sampling rate (such as 44.1 / 48 / 96). It will then send this “clocked” data over
the digital cable. The COAX/optical
works well here. However, this is where
HDMI cable will be severely compromised.
The HDMI transfer is not raw bitstream data. It is done in data packet format, which means
these “clocked” PCM frames will be spread across and combined into multiple
HDMI packets. This means the “clocking”
of the audio is already compromised when the processer/DAC tries to “un-wrap”
these HDMI packets and send it to the DAC chip.
So, as a comparison:
2 channel 24/96 through digital COAX. One weird behavior of the Krell processors is
that it down-converts anything coming in from digital spdif to 48khz. I don’t know if other processors do this, but
this has been normal Krell behavior for a long time (they must think it is a
licensing restriction). Even though my
24/96 songs are down-converted to 24/48, the sound is still amazingly
excellent. The sound from COAX just sounds
so much more “natural” and has excellent dynamics and excitement. I love listening through this mode. SIDE NOTE: I have tested my Oppo player
connected to a DAC through digital COAX and the DAC is receiving and playing
24/96 and 24/192 just fine. It’s the
Krell that is down-converting to 48Khz through COAX/optical.
2 channel 24/96 through HDMI (i2s)
interface. On my Krell, this was the
only way to get the Krell to play true 24/96 or 24/192 at those proper sampling
rates. I can hear that the resolution of
the audio is better than 48khz through normal COAX. However, the sound is more “controlled” or “flat”
sounding. There is no real dynamics or
excitement to the sound. Also, the upper
mids are “shouty” and have “blare” which can sound a little painful at times.
So, to sum it up:
Digital COAX/optical – compromised bluray
audio, but excellent 2-channel audio
HDMI – excellent bluray audio, but
compromised 2-channel audio
