Are there passive attenuators that don't zero volume and only offer one input ?

What about using those keyboard fingers instead, to design your product so that it can have more than one input, and can have silence at zero volume, ... a far better use of your time I should think.

Can't do it, because you are him!!!!

 
I am happy to ignore that reason, as  it has absolutely no relevance at all, relating to what customers want from passive attenuators.

We each know LDR passives offer so much better audio than other attenuation methods, and the task ahead is to make LDR passives the number one choice, as nothing else, can do what they do. 

The good news is each issue, namely more inputs and silence  are relatively easy to do.   I am very sure your customers will welcome those new features, and thank you,  for caring about their needs.,

on a wider perspective ... it will see see all other passives, .. eating dust.

±0.1VDC 1mVDC ripple is hardly anything to sneeze at.
Thyristors make gawdawful noise when switching. Pointless to control current in a device using a few mA.
Quit digging.

Let him go ieales, never have I met such a persistent BS'er as him, for years now on many forums trying to make a quick buck from the gullible, he’ll self implode one day.

Cheers George