I've got a Buffalo III DAC that I put together using Placid HD v1.0 regulator, Trident v3.0 regulators, and AVCC 2.1 regulator. I built it with the earlier version of the Trident and AVCC regulators and upgraded them in late 2012. Recently I noticed that the right channel of my DAC had stopped working. I poked around and discovered that the voltages out of the AVCC regulator were far out of spec. The right channel was down to 0.88v and that channel had stopped working. The left channel was down to 2.7v and was working.

I popped the old AVVC 2.0 back into the DAC and that cleared up the problem. Both channels now regulate to 3.5v and everything sounds fine.

Any idea on what went wrong and if it's something that could fixed? For the output stage of my DAC, I force the outputs into current mode by using 20ohm resistors between + and gnd and between - and ground. I then step up the signal with some transformers and buffer the output of the transformers with a jfet buffer. When working it sounds very good but perhaps puts a harder load on the AVCC regulator than the standard voltage out mode of operation.

Thanks in advance for any feedback / advice.
---Gary