tricky yes xD
When I mentioned letter H, I ment on Candy-branded machines, as we are talking about them xD
Ofcourse I knew the letter Z was used with Hoover machines.
Now that you mentioned that there was available whisper quiet in 2004, I have to correct myself, as I found out that there was a Candy Smart CN 146 HTXT that in 2004, with info text display.. so that way we can make a new reply: Candy never stopped having quiet machines available, it just changed the type of quiet motor, and that's it
However, Aldo's CB 60 AT has that old style motor, however it is produced in 2004, but he bought it in 2005, as it was probobly waiting sometime in stocks of both Candy, and store where he bought it

After being produced, it is normal for machine to stand for 6 months or even more before it's turned on
Dex