Tonky,
You asked "I'd like to know if the 740A was as good as a Pioneer A400" well this is my experience.
The CA 740 has a DIFFERENT sound to the A 400, I didn't like it at first, but after a few hundred hours of running in it has started to sound better. However If like me, if you have been used to the Pioneer for many years, you will find the 740 sounds restrained and a little harsh on the treble (it does settle down after a while).
The pioneer is more fluid and sounds more dynamic in my opinion but It's not quite as good as the Cambridge for revealing little subtleties in the mid range.
So this answer to your question "is the 740 as good as the A400" ? Well, I would say maybe! They are both cracking amps but have different presentations.
which one do I prefer? I'm going to have to say that they A400 would take the prize, although mine has a slight mains hum through the speakers when switched on.
Tesler.