I need to take my Diezel VH4 to a shop to be biased and possibly repaired. I already tried one shop and had less than stellar experience. Don't want to take any more chances and would like to take it to a reputable shop (preferably an authorized Diezel shop). If anyone knows of a competent amp tech around NW Chicago suburbs or the city of Chicago (within 40 miles of Buffalo Grove, IL 60089) the info would be greatly appreciated. Cheers.