I bought a RZ4 300D on Amazon from DiscountCentralOnline and would like to share my experience. I originally ordered one about three weeks ago. It arrived and I installed it only to find out the front channels were defective. I contacted them through Amazon, which was the only way I could. They give an email address and a phone number, neither of which they replied to. I explained I didn't want a refund, just send another amp. Instead they refunded my money, so I ordered the amp again. Later in the day I got an email saying my order had been cancelled. The explanation was it was my shipping address. I reordered it a second time, and again it was cancelled. They said their system wouldn't accept my address, even though it's the same address they originally shipped the defective amp to. Unfortunately they are the only seller on Amazon that carries the amp. Just wanted to vent, and spread the word in the hopes I might save some other forum member the same headaches. Terrible service. How can they ship to an address, then not be able to ship to the same address a second time? I gave up and ordered it from another source. Hurry up and get here, my sounds have been down for too long.