Just joined the forums today, though I've been searching and visiting for a couple weeks now. There's some very intelligent discussion around here, and I look forward to participating. I just picked up a Harman/Kardon Sig 2.1 amp (refurb) from harmanaudio.com via eBay for a real steal at $493. After a bunch of shipping hassles (nobody home to sign for it), I finally got it after work yesterday. The sound quality was stunning. I was amazed at the improvement over my previous reciever (H/K AVR5). I've never heard my Paradigm Monitor 9v2's put out such clear, full sound. I heard small touches in my favorite music that I've never heard before. Very impressed. This morning before I left for work though, I was quickly disappointed. I put on some music at a low to moderate level, and went down the hall to finish getting ready to leave. After about five minutes of music, I heard a "POP..bzzzz..." from the room. I ran down to discover the amp had put itself in protect-mode. Repeated power-cycles did nothing, and I even unplugged the speakers to see that it wasn't a short or something. I think the amp was just plain defective. Anyhow, to get to my questions... 1. Has anybody heard of similar issues with this amp? I'm sending it in for a replacement ASAP, but I don't want to have continued problems with it. I've had one too many computer monitors that have to be RMA'd multiple times. 2. I couldn't hear the volume of the pop. I was in a hurry to leave, so amid cursing I quickly swapped the speaker cables to my original reciever (which was acting as a pre-amp with the sig 2.1) and listened. Sounded fine, but I won't be able to do a good check until this evening. Does protect mode protect the speakers for damage? Or could something have still occurred? So I was VERY impressed with the signature amp until this morning. Hopefully I'll get a replacement and the new one will be just fine, so there's probably nothing to worry about. But I'm overly-paranoid about my system.