They are basically alluding to the fact that they are maintaining an exact temperature for critical clocking components. It holds merit, many leave DACs, or ADCs, on all the time. My fully tube rectified amp takes 20 minutes to stabilize, it sounds like %$#% before then (it has 3 sets of tube rectifiers/regulators).
A lot of audio companies use marketing and hype, but in the case of Antelope they back up every last ounce of it with a quality product and imo the best DAC I have heard in my 10+ years of trying lots of stuff out there. The Zodiac+ speaks for itself, if you ever get a chance to demo one you will definitely understand my passion for the unit.
Also, a simple search in google will tell you what an oven controlled clock can do.