Just to answer a few questions:
"So it's a Meier design made by Shanling?"
Yes, the amp indeed is build by Shanling. However, all the designs, including those of the PCBs and the enclosure were done by Meier-Audio. Granted, the enclosure looks very much like the Shanling designs but that was done to keep costs low. To make a more different enclosure would increase costs considerably. And to be honest, I do like these enclosures. Pictures really do not do the amp justice.
"so it's made in China? or simply assembled in China?"
All the parts to be used (brand, model) have been clearly specified by Meier-Audio. Some parts could not be organized/provided by Shangling. These were either send by Meier-Audio to China or, if not critical for sound, high quality replacements were provided by Shangling.
For instance the NEUTRIK headphone jacks and the BUF634T were send from Germany. However, the polypropylen capacitors made by Vishay that I normally use have been replaced by WIMA versions. The same for the low-impedance electrolytics that have been replaced by Nichicons. All high quality stuff. As said, there are hardly any sonic differences between the very first prototype and the final test-amp that I received from Shanling. If any the latter sounds even better, as it has a better powersupply.
"but is prototype hand-soldered by Jan himself and real amps are made by Shanling?"
The prototype in principle is a modified HA-1 MkII. It has the same powersupply but I did make this amp to test a new circuit topology that allows to eliminate a non-linear parameter that is an inherent property of any normal opamp circuit. The final ARIA design comes with this new circuitry and a better powersupply (and with a crossfeed filter and an USB-DAC added).
"Someone stated that the components are also made in China."
That is true for many products made in China. However, with the ARIA it has been clearly specified what parts have to be used. Many have been made by non-China manufacturers like Burr-Brown, National-Semiconductors, WIMA, NEUTRIK, ALPS, Bulgin, Texas-Instruments, Lumberg.
Be aware that Shanling is a true High-End, high-quality manufacturer that also produces for many other very renowned (non-Chinese) High-End companies.
"What sort of DAC sits in the Aria and how does it compare to say, a Creative Audigy 2 zs?"
The PCM2704, made by Texas-Instruments is a rather simple DAC that also can be found in the PORTA CORDA MkIII. However, thanks to a much better powersupply and a very carefull implementation the sound is surprisingly good and although I have no personal experience with a true High-End sound card I'm pretty sure that the ARIA will be able to compete pretty well.
"why there's no "medium" crossfeed setting, only "low"."
The new circuit topology mentioned above did have some consequences for the implementation of the crossfeed filter and made the addition of an extra filter setting rather complicated and expensive. Therefore the choice was made to implement one level only.