Wilfredt - I use a variety of amps on the Canterburys. There is not that big of a difference in the areas you describe. Yes, there is a difference, but it's not overwhelming - whether it's the Viva 845 amp which only has one 845 output (the 3 211s per amp are rectifiers & drivers), a ss Pass XA 30.5 or other amps I have on hand.
I tend to think your issue is more about how your Canterburys are "playing the room."
Of course, I could be very wrong, but those are the symptoms you describe.
A particular tube or even an amp is not likely to solve the issues you have described.
Worrying about how the electrons flow through a device is miniscule compared to addressing the acoustic wave launch into the room and how it is received - IMO, of course...
I tend to think your issue is more about how your Canterburys are "playing the room."
Of course, I could be very wrong, but those are the symptoms you describe.
A particular tube or even an amp is not likely to solve the issues you have described.
Worrying about how the electrons flow through a device is miniscule compared to addressing the acoustic wave launch into the room and how it is received - IMO, of course...