What is a class G amp ?

Here is some reading :

http://en.wikipedia.org/wiki/Electronic_amplifier

I had a Class G Hitachi SR-804 receiver I bought in 1978 for years. It was a good but not outstanding sounding piece. Not familiar with the Arcam though.

Hadn't heard about Class G in years.

Class G enables higher peak power delivery in a smaller package compared to Class A/B is my understanding.

Newer Class D amps are the more popular amp technology it seems these days for those looking for more bang in a smaller package along with lower acquisition costs and power consumption benefits.

Often class G would be used in portable headphone amps. On rechargeable lithium battery these little ones can last upto 30 hours of continuous listening. It has advantages over A/B class almost on every aspect you can ever think of including clarity, noise floor and certainly efficiency. Call it improved class D.

"Call it improved class D"

Or is Class D improved Class G?

Class G has been around longer but never seemed to break out in home audio.

I suspect class D is more efficient. Also its no comparison soundwise between the Class G Hitachi receiver and current Class D Bel Canto ref1000ms I have heard. The Hitachi was not even close to being in the same league, though comparing a 30 year old 50 watt/ch (100 w/ch Class G) receiver with recent technology 500w/ch mono blocks is certainly not an apples/apples comparison.

maybe some others who have experienced both Class D and G can comment.

My gut feel is that Class G is a simpler technology for a Class A/B amp maker to implement for efficiency purposes than Class D, which a totally different beast from a design and technology perspective. Outside of that scenario, making a more efficient amp using more traditional amp technology, I suspect that Class D has the bigger upside in terms of its value for producing better sound quality in a smaller package that is also most energy efficient.