I'm looking around for a very clear/transparent balanced volume control with attenuation in ≤2dB steps, across the range -40dB to -85dB (though if it went to -100dB that would be a bonus).

This is for feeding my balanced beta22, my source has a low output impedance.

putting a fixed attenuator before my present goldpoint attenuator would mean it could start at -40 but couldn't cover the whole range in ≤2dB steps.

transformers/autoformers appear not to go this low

options I can see are maybe:

MiniVol

MiniVol PGA2320 Volume Control - error404's Audio DIY Endeavours

though I'm no good at coding

lcduino1

The LCDuino-1 display I/O processor

once it gets finished

Anyone know of some more ?

budget for an ideal fit would be

Penny and Giles RF15. Though if you really only need the range of -40 to -85dB, methinks you have way too much gain in your rig, and would be better served by first rectifying that.

custom stepped attenuator I think would be your best option..

The gain of the balanced beta22 is 2 (so effectively 4), the present source I have is set for +4dB. I've not spotted any recommended amps that operate at less than unity gain and most sources get made for +4dB or -10dB, either way I'll likely need attenuation. The world is loud

looking at the RF15 pdf http://www.controldevicesaudio.com/FaderPDF/RF15.pdf it seems that it goes to -60dB then rapidly drops to its -90dB cut-off in the space of rotating 14 degrees.