OSA MP-1 500 Series API 512 Style Preamps in Phoenix, Arizona For Sale

I have two original OSA 500 series preamps developed by Dallas Upton personally here in Phoenix at the Conservatory of Recording Arts and Sciences. OSA was among the first to develop a true API style pre for 500 series. These pres are fast, warm, punchy and amazing. They use Dean Jensen transformers, and are very much like the API 512 preamp. These pre work, sound and looks great.
These were used for about 4 albums worth of material for Izzy Epstein at Schnebly Hill Recording Studio.
This listing is for the modules only, and does not include rack or power supply. These are $250 each unit.
Cash only, no trades.
Thanks.