Thanks for the ideas...
(1) There are two versions of the Grado Master 2. I have the low output version, 1.0mV, which sounds better. I suppose I could take the output of the phono preamp (2V) and drive it into the input of the RIAA encoder/converter... hmm... I got two phono preamps of sufficient gain, but the one in tubed CJ might not have the bandwidth, for sure the the Grado preamp (solid state) does. I think.
(2) The guy on eBay believes his passive converter has the bandwidth. He also has an active one... I'm awaiting for his response.
If (1) and (2) above work, that ought to be kludgy but it will work.
(3) Those old vintage receivers only support MM cartridges with 47Kohm loading and gain for a 5mV cartridge.
(4) The step up transformers, as a rule of thumb, don't have the bandwidth, or so I'm finding out. That was my first attempt, to get a step up transformer for my Grado to drive the CD4 decoders. Mind you, that route ain't cheap!
(5) Hmm... maybe just driving a 30Khz carrier signal might trigger the "radar" detector... that ought to be easy to do. Just need some software to drive a 30Khz detector and drive that one of my DACs at 24/96 encoding (the DACs have sufficient bandwidth for this).
(6) I ought to note that I don't have a CD4 calibration LP... only a handful of CD4 LPs I got over the years... and a few QS/SQ as well. This is not meant to be a long term set up, just a test rig to ensure the hardware works. If i set up four Maggies for quad in my living room ( hey, I have the stuff to do it, I got a spare set of 12s and the amps to drive them: Aleph 2s in front, Aleph 5s in the rear and the Kimber 4TC cables to reach...) my wife will surely kill me.
Hasn't anybody else done this before?