That's a tough one as I used them with Millenia micpres which introduce no objectionable noise themselves.

I went with the lower sensitivity because the output seemed fine in the uses to which I put them. Dave Spearritt tried 4091--perhaps you could arrange for a trial of 4090 and see for yourself-- that is really the only way you can know for sure.

For a main pair I would likely try the 4090. Someone earler mentioned the Shure omni/cardi (KSM141?)-- they have been described to me as being OK for spots.

As you can see by now, everyone has a different threshold of noise and non-linearity!

Rich