Ian, I can only add that Logitech's customer support is second to none, or at least on a par with Bose.
There are several who had a problem with the 2200s. They called them up and were all sent a totally new system and told to keep the old one!
I have two Z2200s and a Z5500. The 5500 is used for surround sound on my TV in the living room (WAY overkill, I know).
One of the 2200s is my computer sound system. The other I keep in a bag for a backup or second pa system. I have played up to 50 or 60 people with it with no regrets.
DonM