Thanks for the info, analogsurviver.
Just wanted to update everyone on a few things.
The issue with the right driver progressed to the point where it sounded very faint most of the time, like Sam reported on his set, and periodically it would crackle and "pop" back to normal volume before falling quiet again. I tried something: putting the channel balance to the right side all the way and turning the volume up a bit past what I'd normally listen to, and it caused a lot of distortion in the sound, especially in the bass. Lots of popping and clipping. However it seemed to force the driver back to a normal volume again, albeit with distortion. Not to mention the left driver was squealing again. Dismayed, I unplugged the headphones and e-mailed Manfred who said he'd be glad to take a look at them if I shipped them back (he didn't mention covering shipping however, so I'm assuming I'd have to foot the bill, which is unfortunate).
However something strange happened. When I came home for my lunch break and plugged the Floats back in, the sound was fine on the right side. The driver seemed to be behaving itself. Puzzled, I continued to listen, and I noticed no more crackling or cutting in and out at that point. The left driver still had some faint squealing every now and then (usually after listening to music for a while). But the issues seem to have subsided largely.
This morning I've plugged them back in and the issues are still not present. I'm keeping my fingers crossed, but I don't want to get my hopes up too much yet. I'm still considering sending them in for inspection regardless, just for peace of mind. I'd be worried about the issue happening again out of the blue.
Now that I've been able to listen to these for a while without fussing about QC issues, I've been able to formulate some very early impressions.
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I don't want to say too much yet, as it's still quite early in my evaluation, but so far I'm really impressed just in terms of sound quality alone. Impressed enough to where I'm willing to deal with the hassle of getting these serviced across the globe. Their tonal balance seems quite linear in the mids and highs, actually somewhat reminiscent of the SR-009 in their accuracy, though they strike me as slightly less bright in the upper region. Their sound has a definite electrostatic clarity to it, but with a lower-end weight and voluminous body more akin to the LCD-3. In fact, I'd say the bass may be a wee bit too prominent on this current setup (ie. with the Leben). When paired with a more transparent amp however I suspect it evens out, something I could partially confirm with a brief swap-out using a lowly T-amp (these STILL sound amazing even with a T-amp). The midrange is pure 'stat goodness, open and clear. The overall presentation is detailed, but it's far from analytically sterile in this regard, avoiding the "hi-fi sparkle" pitfall many audiophile headphones succumb to in an effort to throw details in the listener's face. In terms of pure detail extraction however, it's not going to outclass the SR-009 in my opinion.
One thing it has going for it however that no Stax can quite match is its spatial presentation. Likely due to the design of its drivers and frame, the sound "beams" in a manner similar to the K1000, Qualia, and H2+ (not to mention the original Floats). Like these headphones its sound possesses a truly expansive character that psychologically extends well beyond the confines of the headphone frame. Imaging and instrument separation are quite stunning, and there's a truly addictive sense of depth with these headphones. However as of now I still find the TakeT H2+ to be the top contender when it comes to conveying a sense of presence. Also there's something unusual about their presentation that is both really enjoyable but also a little distracting. It's most clear to me with vocals. Since lead vocals are usually front and center in a track, I think it's a helpful illustration: with the SR-009, center vocals sound like they're centered but somewhat in front of you; with the Floats, they literally sound smack dap in the center of your skull. Sort of like with IEMs that give a more "heady" presentation versus the more externalized sound of fullsized headphones. Oddly enough, everything else that falls outside the central-most point of a track's space sounds very distinctly "out there" relative to the listener. It's a strange combo, to hear instruments psychologically well beyond the frame of the headphones, but vocals (and other centered instruments) sound like they're between your ears. Takes a little while to get used to, but overall the headphones are very non fatiguing, and I could listen to them for a long time in a single sitting.
Thus far I can say I'm both thrilled and also exacerbated. In terms of sound quality, these headphones are shaping up to be top contenders, worthy of a place alongside the stats of Sennheiser and Stax, the esoteric piezo H2+, and legendary orthos. The biggest issue however is their build quality, which has been a major disappointment. The fact that these sound so exceptional to my ears only makes the QC problems all the more frustrating. I feel it's worth the effort of getting them fixed, and if the problems can be sorted out, I think I'll have a new favorite headphone.