Got the Sigma pads thanks Birgir They don't work as a drop in replacement, too thin, but using them as a spacer between the driver and the Lambda pads it turns out is a good thing, better fit and comfort, and more cohesion in the sound, the bass is no longer like its always coming from slightly behind the head. The drivers also aren't so notably bright without the filter this way either, more a matter of taste than necessity.
*Insert O2 killer in the making remark*