Benchmark DAC2 HGC 在 Ubuntu 14.04 LTS 下使用 USB 沒有聲音的問題

記得剛買來的時候是有聲音的,後來突然有一天沒聲音... 試了一堆方法都沒用 (換 kernel 版本、禁用 xHCI、換 USB 線、...),最後是在「Benchmark DAC2 HGC impressions (and Linux setup notes)」這邊看到方法。


DAC2's USB 1.0 mode doesn't work with Linux kernel 3.8.x, but USB 2.0 does. So switch it to USB 2.0 and forget about it. Next, I figured that the audio was simply being muted in some instances. The solution is to open a terminal window, run AlsaMixer, hit F6 to configure the DAC 2. Even though their levels cannot be altered (they're fixed at 00), the first two items must be unmuted in order to get any sound:

如同文章裡說的,USB 1.0 模式 (會抓到「Benchmark DAC2 USB Audio 1.0」) 是不會動的,而 USB 2.0 可以 (會抓到「Benchmark DAC2 USB Audio 2.0」),但播放時沒有聲音。

解法則是使用 alsamixer,進入後按 F6 選 Benchmark DAC2,將前面兩個用 m 給 unmute 掉就好了:

為此學到一堆底層看 USB 的工具...