I have purchased from eBay seller "hellogadgets" two of MV-OP1 compatible expansion boards and installed in my MV-8000 and MV-8800. Currently on my MV-8000 I have the most expensive board with 8 x analog out, ADAT out, extra RBUS MIDI I/O. I have been using the extra analog outs to feedback into MV analog input to drive the COSM Virutual Analog Synth as a pseudo-compressor (VCA/VCF) of my baseline with ghost kick feeding input as side chain trigger. Also, the extra RBUS MIDI out added 16 more midi channels (48 channels total) to drive my outboard MIDI keyboards and synth modules. I have been very satisfied with this upgrade.