Hi,
I didn't have a reference per se. My main goal was to improve on the Low-Frequency extension compared to most STAX out there and we achieved that. Here are the graphs vs the 009.
I wouldn't get into my subjective opinions but I've had two people, one 007 MK1 and MKII owner come and place an order on the spot and another 009 owner who also couldn't tell apart the 009 from the RR1 apart from the LF response being more extended on the RR1.
Anyway, here is the link with the Measurements (I have an upload limit here) - https://www.dropbox.com/sh/3rev8hq54sd3feu/AACb7Zs1DFcKZFYhs3co7Ecta?dl=0