Hi Guido,
Yes, the Aeris has the FPGA but also the AD1895A asynchronous sample rate converter connected to it.
Sure, I understand that your only digital source is the S/PDIF output of the X-01.
To be honest with you, the X-01 requires some redesign work in order to become a good sounding digital transport, at least to my standards. It is also possible converting the X-01 to a CD/SACD transport that will work with the DSD-S via proprietary digital connection.
CD data is converted to double DSD128, while SACD is native DSD64.
The audio quality achieved is quite nice. :-)
Saluti,
Alex Peychev
APL Hi-Fi