Update on the new gear - this is a unique amp (as far as I know) that has four gains; high, low, fast & slow. From what I can tell given the lack of info (we all know Kingwa needs an English technical writer), my hd650’s respond noticeably better on “fast” mode. Got less than a week of use thus far on the amp. More to come.
Oh, if it were only that simple...
Really, there only two levels of gain. The website lists the gain at +16db, which seems like that's only for high gain since the unit can put 9000mW or so into 32 ohm. By contrast, my Violectric puts out under 3000mW at 32 ohm and has its highest gain at +12. But, that's just a guess.
Here's what the "Use Manual" says for the 28.38:
Gain button:
Select the Fast / Slow volume control characteristics.
H: Fast. 64 steps range.
L: Slow. 100 steps range.
F: (Full ) High gain mode. 100 steps range. (For the low sensitivity headphone like the HE-6 or the source had low output voltage level)
S: (Super)High gain mode. 64 steps range. (For the low sensitivity headphone like the HE-6 or the source had low output voltage level)
Fast and Slow (H and L) are Low gain, while Full and Super (F and S) are High gain. From experience, this seems to be the case as well. The 64 step options are for quicker control of the volume. If you use the amp at 87 out of 100, switching to Fast means you can run around 48 out of 64 instead. They've got a graph here may help understand the idea:
http://www.audio-gd.com/Pro/Headphoneamp/NFB29/NFBvolume.jpg I tend to use L or F because they offer finer control of the volume, but there doesn't seem to be a difference in sound quality between them and the 64 step versions.
As with many aspects of Audio-gd, the 28.38 UI and explanation thereof are weird and confusing.
Good thing it sounds glorious.
