I kinda "made it WORK !", I found out that... if you throw mp3 songs to the voice folder.. the XVR just play them back right away. But... if you record a voice from a microphone and save it as mp3 (or export it as mp3 from several formats) for some reason it does not work... tried with the smart...
it was not obvious to me at the beginning ... that the RCA audio output IS NO amplified (you can't just connect a regular non amplified speaker), at least I could solve the cabling, amplifing aspect, now it's all codec playback related, apparently...
I am "close" but it's not enough... if I try several times to play the mp3 file, every once in a life time it works, the rest of the times the audio makes a click noise and stops... It seems lik a buggy feature to me... not fully deployed yet... may be next firmware... ?
I have the same issue on my brand new XVR5108H with latest firmware, I managed to upload a few Mp3 to the device but still no audio out... maybe I have to change the plug adaptors, something to do with the RCA to 3.5 mm male plug ... or I dont know, its not only that the voice prompts do not...