HI,
no, the cards are not the same.
The OBXa has two filter chips and the OB-SX one i.e.
The OB-SX is also more or less a mix of the OBX and the OBXa. It still has the X-Mod from the OBX
and as far as I remember a different VCA
Best,
Thomas

Thomas P. Heckmann
Trope Recordings - AFU Limited - AFULAB - trope mastering