Has anyone used Richer Sounds for a repair? If so was the experience good? I have a broken Cambridge Audio 851E pre-amp and I am thinking of going back to the original seller because I am assuming they have knowledge of the brand and possible the model. For the curious, the amp died on switch on. I found a blown internal fuse which I replaced but on switching on there was life briefly before a small puff of smoke and the amp died again. This time, rather worryingly the fuses are intact. Thanks in advance, Andy.