I'm Ben from Cambridge Audio. Today I'm here to tell you even more about USB
audio and how to get the most from Windows. USB audio is an audio connection
which is used to send digital music from a computer to a DAC. We've seen that
audio is sent as packets of data down the USB cable to the DAC, but with
Windows it's what happens before this inside the computer that has the biggest
impact on sound quality. There are three main parts to any USB audio system
the media player, the driver and the USB DAC itself. Macs are nice and simple.
They support Class 1 and Class 2 USB modes letting you listen up to 24/192
resolution music straight to the DAC. Windows computers are a little bit more
complicated, but a few simple steps can be taken to improve the sound quality
from Windows making it as good as a Mac. But first we need to understand how the
Windows audio system works.
Kernel streaming is used by Windows to send audio from the media player to the
audio driver.
The problem with this is at the same time the Windows kernel is also dealing
with Windows sounds such as mouse clicks and notifications and other programs
which create audio. The audio signal is then mixed in with all of this and gets
distorted because of that. When you plug in your USB DAC and select it as the speaker
you will automatically be using direct sound, a type of Windows kernel streaming.
It only works in Class 1 USB mode so is limited to playing 24/96
resolution music through your DAC. It works but unfortunately DirectSound has
high amounts of audio distortion, so it's not the ideal setting. WASAPI which is
short for Windows Audio Session Application Programming Interface is
another type of kernel streaming. WASAPI still only works in Class one mode
and only lets you play up to 24\96 music, but it sounds much better than DirectSound
because it keeps the audio signal separate and doesn't mix it with Windows sounds.
But to use WASAPI you need to use a media player like foobar 2000 or JRiver
which supports it and then select WASAPI as the output setting. Otherwise
you'll still be using direct sound. iTunes Spotify etc
can't be used with WASAPI because they don't support it.
ASIO or Audio Streaming In Out is another method of audio transport but
this time it's not kernel streaming. ASIO bypasses the Windows kernel
altogether and avoids any of the audio distortion caused there. It effectively
gives a direct path free from audio distortion directly to the USB driver.
ASIO works in USB class two mode only so you need to install the free Cambridge Audio
class 2 driver from our website. iTunes Spotify etc
can't be used with ASIO because they don't support it. But you can use a media
player like foobar2000 or JRiver which does support it and just select
ASIO as the output setting. Using ASIO is better than all Windows kernel streaming
methods as it delivers far better sound thanks to low jitter, lower latency and
has no mixing of audio streams and Windows sounds. Because it works in class
2 mode with the Cambridge Audio USB driver, it also allows you to send up to
24/192 resolution music to your DAC. So using ASIO brings a Windows computer up
to the same audio performance level as a Mac