Do RADAR and PTHD have analog trims to allow the reference level to be set without the need to attenuate the signal from tape? I don't use either of those formats regularly, but in my experience, when stuff comes from tape the "soft boundary" can allow big transients to exceed 15db from nominal. This works on tape, but will result in "overs" in the digital rigs.
If that is the case, you either lower the output level from the output of the tape machine, attenuate it with the console or something, or trim down the inputs on the digital device if it has such feature. Many converters do not, or if they do they are internal and shouldn't be messed with in ordinary discourse.
Hmm... If you set up the oscillator for +4dbU and align the tape to that, it should come in somewhere near -15dbFS if the tone is passed through at unity. So in order to make "all things equal", one would have to either reduce the output from tape for both listening tests, or correct the difference later by matching output levels when the dump is already complete (if "overs" were ocurring).
Very curious about the results, especially Fletcher, MM, and SA's opinions on RADAR vs. Alsihad with the same material.
Chris