Hi
I recently added the 2X driver. Can you please check the single buffer constructor (without 2X).
I also do not own a Mega Board, so i have to rely on whatever the Arduino.h file has defined for the Hardware Pins.
If these hardware pins require some special settings, than these settings are not known to me.
But in any case, the SW SPI should work.
Your observation might also be caused by the connected hardware. How do you do the level transition?
Is it a HC4050 level translator for the signals? Resistor networks might work, but you might observe
other voltage ranges.
Oliver