The cards are 64gb Kingston - they worked (and work - I checked) just fine in my AK100. I tried rebooting and even a factory reset but the problem remains I'm afraid.
I noticed one of the firmware updates on the AK100 mentioned fixing card reading issues, but then I'd have thought this would have been inc in V1 for the '120... I've been in touch with Jaben and they're going to contact A&K about it - maybe I just have a dud one.
As for the brown case, I cannot like it ;-) I looked at the A&K100 OEM original but it looked dreadful quality - like I'd made it in beginners leatherwork class. The Dignis one from Korea is far superior quality, albeit not quite so protective - talking of which, I'd be well p1$$ed off with such a blatant copy of my work by the supposed Italians who make the brown one!
I concur with the upgrade advice too - we are well into the law of diminishing returns here ie doubling the money for a relatively incremental sonic gain - what I wanted to achieve was what I'd originally hoped for with the AK100, namely to have great sound in a small package. When I noticed a post on here with it strapped to the Vorzugge Pure (that I also have) I realised the pair is better - but they are rather cumbersome IMO. Hence the AK120 gives me what I want - more power and quality in a small unit. Of course, I may be back to square one when temptation gets the better of me and I plug the amp in!
Either way, the AK100 is for sale, and the VZ Pure too, probably.
That's a shame, I actually like the AK100 and Pure with the FitEar customs, I think I read you have the MH334 on that thread?