Mixing power adapters

Hi all, my friend just dropped off an old Next! drum machine with no power adapter - it needs 10-12V @ 300mA. Can I use a rectifier with a higher mA output? I don't have anything laying around the house that meets this spec, but I have some that are close (10V @ 1000mA etc). Can I safely use something like this without damaging  the drum machine or should I play it safe and buy an adapter from R$?

The amperage rating is just letting you know what the maximum it can take is - provided the max is higher than what the device needs, you're all good.
Short answer: use the adaptor you've already got.