My aim isn't exactly to criticise that review as I'm not setup to test to the level of testing they have done (tho my gut instinct is there was some issues with their review unit or they exposed some bugs or had misconfiguration in the sound enhancement settings) if you read their conclusion on the audio quality you'd get the impression that the sound quality on this tablet was sub-par to most other tablets - and from my first few days of using it that certainly wasn't the impression I got so...
I did some subjective listening using a pair of Sennheiser MX580s as I've used these on a lot of tablets and phones and they have extreme clarity and a good neutral reproduction that makes it easy to spot significant issues with sound quality. While bass on them is more balanced than powerful they are still good enough to identify issues there.
The music I use for testing is listed here
(this is for reference purposes - most of the testing was done with lossless compression versions)
In brief:
In tunes like Buildings and Mountains and Jack Sparrow when everything is working as intended the sounds of individual instruments are well picked out with good seperation and definition - I did notice 1-2 instances of lower mid-range distortion which
probably coincides with the 1-2khz part of the graph in the gsmarena arena review everything else sounded as expected.
Seize The Day and Hotel California - good range of percussion mixed with dynamic vocals and high end instruments/keyboard - lots of chances for distortion here but didn't hear anything that was out of line with any other tablet or phone and was handled better than many.
Limit To Your Love - More applicable really to testing speakers/headphones than the sound hardware but whole load of stuff going on here that can break fidelity. The low end effects from a minute in were reasonably well controlled, the complex sections remained clean.
From the best of my ability to tell by ear characteristics probably
are fairly close to what the graph from gsmarena shows, however aside from what I'm assuming is the 1-2KHz issue I didn't see find any signs of noticeable distortion in the rest of the frequency range and the low end bump didn't manifest itself as any issues I was able to reproduce - even using 20-60Hz test tones and sweeps the best of my ability to test showed accurate and tightly controlled low end that was as for all intents and purposes as good as anything else I've listened to tablet/phone/mp3 player wise. Sitting it down and comparing side by side with the galaxy note that they generally praised for having low levels of distortion and good frequency response and aside from what I think is that 1-2KHz area the tablet sounds cleaner and more lively overall.
Crosstalk at the level they are testing can't really be done by ear but most of the tracks I use for testing by their nature will highlight
really bad levels of crosstalk which wasn't present.
So subjectively I couldn't tell that the sound quality in the context of everyday tablet use was any worse than average for a tablet and definitely better than a good number of devices I've used.