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作者: somedy

至于自动降为Class 1，我不是很理解怎么能做到，因为两个规范并没有兼容性。

Class 2 向下兼容Class 1， 请参考【An introduction to computer audio】

其中就提到：

USB Audio Class 2 standard (2009) is downwards compatible with class 1.

作者: somedy

Class 2是异步传输

Class 2 也可以同步传输：

请参考 【MAC Supported USB Audio 2.0 Features】


而且同步/异步谁好，也是很有争议的。

“Not everybody agree that asynchronous is better. ”

“Async can have just as bad jitter as sync if the clock at the DAC is badly implemented.”