Does anybody know of some software (a plugin) which can generate random noise signals at specified levels, e.g. around the -80db - -90db range?
 
I suppose I could try e.g. using a synth which has a noise osc and turning down its output until I get the level I want.  Thing is, at that low a level it's hard to see what the level actually is e.g. using a typical DAW level meter.  It'd be nice to be able to define the level of noise being produced.
 
Any other ideas?  I'm going to have a search on t'interwebs...
 
(edit: needs to be something which is 64-bit)
 
Another edit: I've found something that looks ideal in the Melda Productions bundle (the MNoiseGenerator).    Any suggestions on how to accurately measure very low level audio signals?

If you output noise at, say, -10dB RMS (make sure you use RMS) and apply -80dB of gain you get -90dB RMS.

Never tried this, but I suspect that if you export a silent track with dithering enabled that you'd get noise in the vicinity of -90dB.

Cheers folks!  I've got a few ideas to try out over the weekend now.