Hi, I know this post is a couple weeks old, but FWIW, I actually had a bad amplifier on the same sub. I contacted the folks at ML and they were super helpful - after proving that I had bought the sub in the last year (even though it was refurbished on Amazon), they provided me with a mailing label. I pulled the amplifier out of the sub's enclosure, put it in a cardboard box, and sent it to them. Within a week they mailed me a replacement amplifier and my office 2.1 system was back in business. The whole process was painless and efficient. If you haven't reached out to them, it might be worth doing so. Hope this was was helpful.