With respect, no argument on your experience with the Woos, but I sort of wonder how it can have more details, but not be as transparent as the other one? Maybe there's an issue in how we define our words? I typically think of transparency as the ability to allow details to come through. The more transparent, the more details you are able to discern. Whereas less transparency might be referred to as a fog - details are obscured, get smudged, or can't be discerned at all.
Maybe you have a different take on it, though.
transparency and detail are not the same.
transparency is exactly what it sounds like, see through, does anything get in between you and the music? any grain, harshness, unnaturalness, or noise takes away from it. in a way, yes the way details come through, but it doesn't exactly mean you hear more details, or that there is more. details are just the resolving ability of the headphone, how nuanced is it, how much more information can you hear and how much better is it, however, it isn't necessarily transparent. for example, Beyerdynamic headphones are very detailed, much more than an Audeze, but I wouldn't say more transparent. The Audeze's tend to have a very clean sound to them, though dark, there is absolutely zero grain. The Beyers though presenting lots of detail, tend to have treble grain which takes away from their transparency, it sounds slightly more like a recording and less like the real thing due to this.
The WA2 seemed to be more transparent because it sounded more natural, there was certainly less grain than the WA6-SE especially in the treble, the coherency and presentation of the music was very natural and the noise floor was quite low, almost black background, all these make it quite transparent. The WA6-SE was slightly grainier and seemed to be more aggressive with a slightly more compressed sound, it was fairly neutral despite that, with slight tube warmth, noise was a little more than the WA2. However, the WA6-SE was also more detailed, I heard more things in my music and it was easier to pick things out due to the larger soundstage.
the GSX MK2 for example is one of the most transparent solid-state amps out there, why? Extremely neutral and uncolored, absolutely zero grain, the transients are very liquid and theres a nice fluidity to the sound and dynamics, it sounds effortless, and the background is black. Usually transparent headphones/amps will have more detail, but this can change (like if a headphone is warm or dark, it will be slightly less detailed in the treble, but it can still be transparent if it is free of grain and has a natural tonality).
In a little more extreme example, youtube videos, recordings on cheap microphones/cell phones/etc.... see how easy it is to tell that its a recording and not the real thing? its due to the grain and digital nature of the sound, as well as the sort of muffled sound, that is the best example of non-transparency i can give. take away the grain, make the sound more natural and make it feel like you're closer to the real thing, it sounds like theres nothing between you and the music, thats transparency.
details just means its easier to pick up subtle things in a recording, from spatial cues to notes and instruments hidden deep in the recording.
anyways, thats about as good of an explanation as i can give. DavidMahler kinda explains it as well in his battle of the flagships review, he makes it very easy to understand if you read why a headphone would or not be transparent. with an amp its the same thing, you'll know if it sounds cheap or not
