Originally Posted by NCSUZoSo
From everything I've been told by long time Aune T1 owners, the tube is actually not used the same when you just run line in/out mode on the Aune T1. You can check this by running it like that and pulling the tube, the sound barely changes, if at all. Now do the same when running USB, you have almost no sound. I'm sure the amp section plays a role in this and I would like to know if I was misinformed or not.
The tube is used via USB. Line in will bypass the tube entirely and use the amp only. Line out will bypass the internal amp but still use the tube.
See the FAQ on the first page:
Q: Does the Aune T1 DAC utilize the tube, does the T1 headphone amp section use the tube, or do they both use the tube?
A: The Aune T1 is a USB tube DAC with a solid state headphone amp. What this means is that if you want the benefits of the tube, you must use the USB Input of the T1. The amp section of the T1 does not use the tube by itself. Technically, you could bypass the DAC of the T1 and just use the amp but this type of use is not really what the T1 is for. One thing you can do is use the T1 USB input then hook up a different amp to the RCA out of the T1. This will give you the benefits of the tube and allow you to try a different/more powerful amp (though I think the amp in the T1 is quite good). I personally have a speaker amp hooked up this way so I can use my headphones and some bookshelf speakers at the same time from one source.