It took me roughly 6 weeks from placing order to delivery.
Yes, I received a ZDS. You can tell a ZDS from a ZDSE easily by checking the height of the two black capacitors (between the two 6C33C tubes). The ZDS's caps are nearly twice as tall as those of the ZDSE.
That being said, I think it's a little too early to post impressions as I'm burning in the unit, but here goes. Keep in mind that I also used to own the ZDSE, and while I don't have it now for direct A/B, I've lived with it long enough to know its sound sig and especially how it sounds with HD650/800.
Compared to the ZDSE, the ZDS definitely has a smoother, less fatiguing treble which becomes evident when using the HD800. The ZDSE was arguably the most euphonic sounding amp of the EC lineup but ironically it presented the sharpest treble. I still cringed a bit with the ZDSE/HD800 on certain recordings. While the ZDS doesn't entirely take away the sibilance associated with HD800, it does a better job than the ZDSE did.
Also, the ZDS is less euphonic than the ZDSE by comparison. I do enjoy a touch of warmth and euphony to my music but with the ZDSE I felt that it was a bit too much occasionally. While the ZDS still remains an euphonic, warm-sounding amp, not as much as the ZDS was. This could be a good thing or a bad thing depending on your musical tastes. Personally, with the HD650 I think it's definitely a good thing as the HD650 is already a bit warm/dark, and pairing with the ZDSE could result in an overly constipated sound.
As for the HD800 which is bright, people's opinions might differ, but do note what I said above: the ZDS may sound less warm and euphonic than the ZDSE but it actually presents a smoother, less fatiguing treble. Taking this into consideration, I feel the ZDS is actually a much better match with the HD800 as it tames its otherwise cringeworthy treble without compromising its ultra imaging/resolution/detail retrieval qualities with euphony galore.
And overall, the ZDS has a noticeably increased transparency/resolution compared to the ZDSE across the board. This might be attributable in part to what I said earlier about the ZDS being less euphonic, but nevertheless it is a significant improvement.
To sum things up, I don't regret selling the ZDSE and if I had known the ZDS was this much better for only $100 more I would've sold it and upgraded to ZDS without hesitation. The improvement from ZDSE to ZDS definitely isn't minor like what one would expect from HD600 to HD650, rather it feels like it's in one league above its predecessor, for instance going from HD650 to HD800. I would've guessed an amp sounding this good would cost over $3K, so it's definitely a great value buy for me.
Please take what I'm saying above with a grain of salt or two, since I haven't actually compared them directly and am using different DAC's (I had used Metrum Hex for ZDSE, currently I'm using Schiit Yggy for ZDS).