I also happen to have an outstanding speaker issue that dates back 12 months, but no-one seems interested in fixing a speaker under warranty that buzzes, which raises questions as to whether there is anyone still working there at all!
Let me guess, its 'within spec'. I have similar on Prime PSU - its even been compared next to another Prime PSU that was totally silent - just as I expect them to be. The bit that annoys me, is that on two occasions, either Meridian or one of their reps have said that it was normal (clearly not having compared side by side) and I bet on neither of those occasions was the unit opened up to check inside if anything obvious was making the noise or a simple adjustment could not fix.
I did however get a longer power lead off of them to separate the units to allow the PSU to be moved further away from the listening position! Unfortunately, they swapped it (in the old days I would have got to keep the original) for my original short lead which in its current position I would find rather more useful.
So unfortunately, buzzing kit seems to be 'within tolerance' these days.
Alas, this experience has made me question if I would ever buy Meridian again.