The NOLA Thunderbolt sub uses an A/B amplifier. I haven't heard it, but it's received excellent reviews from both reviewers and users. It's not tubed, but is considered more of an audiophile subwoofer than most.
Any tube subwoofers out there?
I was just wondering out of the blue if there were any tube subwoofers, if not why not. Also are there any class A/B or other types beside the ubiquitous Class D? Just trying to learn more. Thanks