I currently have a QR-6500 and QR-4500. However, would like the Vario-Matrix experience. I'm wondering which would be the better route: getting a QSD-2 to plug into my QR series receiver (currently just using the 6500 in quad mode.) Or, look for a QRX-x001 receiver? If I do that, I prefer the aesthetics of the 8001/9001; however those are fairly expensive and seem to need significant maintenance/are difficult to work on. The 7001 and below would be ok, but no better looking than the QR series. I am very impressed with the build quality of the 6500/4500, and have no troubles with either. I assume the QSD-2 would be zero maintenance? So, which makes more sense? The QSD-2 seems to sell for around $400 on the auction site, which seems like a lot, but the only alternative seems to be buying a QRX-x001 receiver for about that much (5001, 6001, 7001) or much, much more (8001/9001).