Stumped! Ultralite mk3 - no sound but level meters OK

[Bell314159]

Hello,

Hoping that the combined knowledge of this forum might help crack this case, or at least enlighten.

I am running a pair of Ultralite mk3's with Windows 7, for 16 channels of analog output. My configuration is primarily for play-out of multi-channel sound, using Reaper as the source, for live performance (I feed 16 channels of amplification, into 16 separate loudspeakers). My system was running perfectly for months, and then suddenly I noticed that half my output channels were gone: the Ultralite analog outputs feed a 16 channel mixer, and I noticed that the last 8 channels weren't present on the mixer. Then, about a week later, the first Ultralite output signals also disappeared from the mixer. However, the level meters on the Ultralites are there, bouncing around as if nothing's wrong. But no sound at their outputs.

I happen to have a second pair of Ultralite units, so I did a test, and swapped the "bad" ones with the second pair, and my mixer lit up across all 16 channels. However I'm stumped as to why the analog outs would fail, but everything else *appears* to be fine (bouncing digital level meters).

I suppose it's possible that the Ultralite mk3 units both died on me at the same time, but that would seem like too much of a coincidence. But maybe these units are affected by overheating over the long-haul? My units were in a rack without any air-gap above or below. Has anyone else experienced this issue? And if so, have you been able to recover/repair the units (is it an expensive fix)? Could the output stage of both my units be blown?

Thanks for any help!

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Windows 7
Reaper
Lenovo T400 notebook
Firewire