I have an O2/ODAC, which if you believe the designer and innerfidelity, is pretty much reference grade kit, designed by objective measurements rather than by subjective audio/by-ear testing. So, in theory, a top notch DAC and a top-notch amp. For testing purposes I use the famous etymotics balanced armatures (HF2) which is very nearly reference grade as well (for that I would need their ER4P or whatever they call it, which are manually left and right volume matched), which are ultra-fast, super-flat and very sensitive, so super detailed.
I have the darndest time telling the O2/ODAC apart from my onboard/laptop sound card. The only difference I can tell is the tiniest, and I mean tiniest, bit of background noise on the soundcard. To really A/B I would need to have some kind of instant switch between the two, playing simultaneously and level matched (slight differences in volume can affect subjective judgement of audio quality). So ironically this is a subjective opinion. However, based on my experience, if I didn't have other needs then I wouldn't have bothered with the ODAC.
And it's not a 2012 laptop but a 2007. The chipset is SigmaTel STAC 9200. I've measured the output impedance and it is 0.5!!!! What does that mean? It means they haven't cut corners and the output is superiour to older ipods and most macs. I've also tried ringing with a mobile phone bang on top of the headphone-out and receiving a text: absolutely no interference (I was plugged in to my -35db isolation etymotics also with -35db ear defenders on top). That low output impedance is especially surprising. So many gadgets have it high, and that will result in flabby, boomy and rolled off bass, plus loss of highs in many instances. So not only subjective audio quality but, considering the lack of interference, superb engineering/implementation.
The laptop is a Dell D430. Small and nicely built. It's a business laptop. I've also used an older full sized business Dell and its audio was horrific and with no need to test so elaborately as above: it was instant trauma and long-term therapy. Later today I'm going to try out various of the computers and laptops where I am now and report back.
There's every possibility that I've just been lucky; Dell, for some bizarre reason, put a top spec audio chipset with excellent implementation in to this laptop. But without the ODAC/O2 how would I know. My suspicion, however, is that in better, modern motherboards, audio chipsets are a mature technology and effectively hifi. No external DAC needed (amping is another matter entirely).
I am acutely aware how difficult, without proper A/Bing, it is to judge audio except via expensive test equipment, and even then it is subjective (as above). On top of that is my own opinion that a slight degrading of audio quality can make all the difference to aural pleasure, especially with better headphones. Imagine a bit of ringing in the dac, a high output impedance in the amp/headphone-out, + phase issues. Subtle individually but cumulatively significant. And I want the best. This makes the whole issue slightly fraught (for me).
At the same time are the very mixed reviews of external DACs. Not only are they mixed but the darn things are expensive. Very expensive. I;m not at all convinced of external DACS in the main, So what to do?
Well, both subjectively, by popular appraisal both here and on amazon, and objectively (if the O2 designer's tests are to be trusted), the Sansa clip+ is very nearly hifi except for a bit of background noise (more than my dell). So, lacking reviews and objective measurements, I would suggest getting a cheap clip+ and a/b-ing candidate soundcards with that (and some etymotics). If you can't tell the difference then you (probably) don't need an external DAC to have something acceptably near hifi. Plonk in the cheap (also near-hifi) FII0 E5 and you can also correct for output impedance issues without having to get a multimeter and rig up a jack and 33Ohm resistor (plus have a half-decent amp in to the bargain).
