In case of an active, low output impedance IV stage, the best solution is to forget about analogue VC or any kind of additional preamp circuitry. In some systems this may even be possible with passive I/V or voltage out solutions.
you should see the Accuphase AAVA volume control.
imagine 16 current sources multiplied by 4 (x2 for balanced, x2 for stereo).
each is an improved Howland topology implemented with a precision opamp. none of the 'usual' suspects but precision, low-noise types nevertheless. the positive feedback path contains another opamp configured as repeater. each of the two opamps has a buffer at the output (2 transistors). and we should remember that the Howland current source is sensitive to resistor values. so we have hundreds (yes, do the math) of precision, low-noise resistors in the signal path.
somehow it achieves 120+ dB SNR. and the AAVA is only a portion of the preamp.
kinda makes me laugh thinking at the passive volume controls some are in love with. it also makes me wonder if sonic quality has to do with this choice at all. pretty hard to DIY something similar to AAVA. better to talk about how passive sounds better.
just sayin'.