Ahhh... VA==W in the case of linear loads only. Power supplies in computers are notoriously nonlinear, though, and the VA rating of the tranformer needs to be derated somewhat.
I'm guessing that audio amplifiers are mostly linear, though, and that the only nonlinear loads you see on audio equipment are in the cases where you have DC power supplies (CD players, etc...). I'm also guessing, then, that it might make sense to have the CD player (and any other piece of gear that has an AC-to-DC power suppl ...
There is no transformer in a computer switching power supply, unless it's a "Flyback" design. Ref: there are about 20 different switching power supply topologies and only the flyback has a transformer.
And if it is a flyback switcher the transformer doesn't come into the equation anyway, voltage regulation in a switching power supply is maintained by a feedback loop monitoring the supply's output (keeping it constant +/- Tol). The switching rate and /or duty cycle is thus servo controlled to keep the output constant within the desired tolerance.
Computer power supplies are spec'd by output and efficiency (Eff = Pout/Pin) and efficiency varies from 60%-96% depending on the type of switcher. I discounted power factor here for simplicity.
In audio we speak of the power (w=VA) delivered to the load. What the load gets and uses is usually our topic of interest. We can then calculate the power supplies efficiency if desired but most users don't care to.
Most audio loads are non-linear because their impedance (capacitiave and inductive elements) varies with the frequency and an audio program varies in frequency all the time. Loudspeakers are the worst case audio load because they need the most power.
BTW: By definition, watts = VA = joules/second ; this means that the true meaning of watts is the power in joules used in a one second period.