Yes, 1/4-20 is Mirage's thread diameter and pitch. You should be able to find aftermarket spikes or cones in that thread size, such as at Oregondv, which also sells the Soundocity outriggers if you really want some stability out of these narrow footprint speakers, especially on plush carpet.
Need Feet/Spikes for Mirage OMD-15
I recently acquired a set of Mirage OMD-15 speakers that did not come with the rubber feet/spikes that can be screwed into fittings on the bottom of the cabinet. I' m very curious as how they might change the sound of the speakers which are sitting on a very solid hardwood floor. Does anyone know where I might find these items; or what size thread was used so I can look for non-original replacements?