Ok... you want to output sound from your tablet to other equipment, right? Start by turning the volume down in the tablet, connect the headphones output of the tablet to the input of the device you want, start raising the volume to a little bit under clipping level of your other device, or before you hear distorted sound. When you're done, just start recording or whatever you are trying to do.
Anyway, there's no point to have a digital or high quality audio output in a tablet because they're not designed for that, even if you do it before DAC, your files are compresed (MP3, etc) right? . Do you have an extremely high quality song in your device?, if you do, you're probably a sound engineer, a professional musician or an audiophile and if that's the case you'll transfer the media to a more professional device or a dedicated media player.
For example, those cellphones that have hdmi output, yes is a good idea to connect it to your TV right? now, do you think the video you are playing through it has a great sound quality? NO, specially if it's some internet video... Putting things more simple: the audio quality of the actual media that's coming out your tablet 98% of the time does not have the quality to merit a digital/high end connection.
Now, there's a brand called COWON that has the best sound quality in media players, (Yes, best sound quality by far over Aple, Samsung, Sony, you name it, this is not because I say so, do some research and you'll be surprised) they don't make Tabs sorry. So if you really are concerned about audio quality, you should convert your music to Flac instead of MP3 and go for a device like that, otherwise you are wasting your money in technology when your source doesn't have the quality to match it.
You see what I mean? a Tablet is a portable all in one device, for high end video and sound you need a more dedicated device
Do they have a cellphone or tablet with a hdmi output? what do they have in there? a Bluray movie? it would be soooo compressed that it loses the point of having a HDMI output.... why? because compression equals lower quality. So it's like having a Ferrari with bicycle wheels... Doesn't matter what the vendors tell you, to have a HDMI output in a cellphone it's just ridiculous, and whoever has it they probably use it a couple of times and they forgot about it because there's really no point on that. The only thing I can think of having a HDMI output in a tablet is maybe someone that needs to make a video presentation, maybe through a projector, something like that, and you don't need high end audio for that. The Tablet makers don't care if 1 person out of a million needs it, would you? And... Actually do they really need that? or it's more to impress their girlfriend or a neighbour? F*** That!! Right?
I'm not trying to offend anyone here, I'm just trying to help you understand that it really is pointless....
The technology will evolve eventually and we will have better audio hardware in our tablets.... and a lot more memory to have those HD files that we really can't right now...But by then,,,, are you going to enjoy that quality in a $14.99 headphones?
With all this I'm not saying be happy with the crappy sound your device could have. I actually returned a few days ago a Galaxy Player 4.0 because I didn't like it's sound quality, I'm buying (when it comes out) a Cowon Z2..... can't wait. (if I have the money by then)
Take care guys, I hope I helped a least a little...