I've had a QR-1500 since 1974, and aside from cleaning the slider-pots and synthesizer push-switch with DeOxIT, I've had ZERO problems with it. The quad-synthesizer works quite nicely, and although the power output sounds weak, that silly 7.5 watts per channel (through good speakers) will blow you out of the room. It's all "discrete" components in a direct-coupled arrangement, so fixing problems (I used to run a shop) was very easy. T. Carl
