i have the 536A and while it was a nice unit - i just don't use it anymore. it sits in the rack very lonely with an old digitech fx unit. i guess i thought i might break out the orban for some sibilant female singer, but everything is done in the box now a days for that purpose. just don't use it, in fact if you haven't found one for sale yet, i will be willing to part with mine.
let me know...
and merry christmas to ya'
...champagne for my real friends, and real pain for my sham friends... Tom Waits