I bought a 4x12 from Craigslist about a year ago. The guy was honest about one speaker being replaced, same as the original, a Vintage 30. I never opened it up, sounded great and like I expected. Today I opened it up to do some other work and noticed that indeed one speaker was replaced, but while the originals were all 16 ohm V30s, the replacement is an 8 ohm. I've been using this cabinet for a year and have had no problems, but what exactly should I be concerned with here? I've heard that ohm mismatched can burn out transformers, but that hasn't happened yet thankfully, so maybe the mismatch is small enough that it's not causing damage. I'll be replacing it soon enough to ease my OCD, but I'm curious.