I guess I'm in the "I'm so stupid, I don't actually know" category.
I have a Sunfire TGA-5200 which is a solid state switching amplifier, but some websites say it is Class D and some say it is Class H.
No worries, Sunfires are hard to categorize as they’ve been variously called Class G or H, but they are definitely NOT class D.
But just like the G/H, it is basically a rather conventional Class AB type; there are no switching devices in the audio amplifier channels. What makes these amps unique is their power supplies.
The Power Supply IS a switching type supply but it is unique in that it tracks along with the music signal. The supply is essentially a regulated power supply but instead of using an immovable static voltage reference (almost impossible to achieve), it uses the music signal itself. The advantage to this is that the output transistors of the amplifier do not have to dissipate the heat produced by having fixed power supply rails that are significantly greater than the average signal level. At idle the output transistors see only about 8.5 volts across them. As the music signal increases, the supply rails continuously track the signal. At full power the supply rails approach 120 volts. As a result, the Sunfire amps have no heat dissipation devices and yet still run cool.
Another advantage to these amps is that they cope extremely well with low impedance loads. The Sunfire amp will double its wattage into 4 ohms, double it again into 2 ohms, and if your circuit breaker can stand it double it again into one ohm. Perfect for ML’s
Therefore, it really falls more to a Class H attribution, than a Class G, since it has an infinitely variable power supply. But it’s not exactly a ‘pure’ H.
Here's a great article on Sunfire amp technology
And the Wiki on amp classes
