I’d like to use 100V equipment in Australia, is this an issue?

No, as long as you understand the implications and have a quality step-down transformer of the correct power rating.

Such a transformer should be from a quality local manufacturer like Tortech. It should be rated to deliver 1.5 to 3x the rated maximum power consumption of the attached equipment.

Obviously, if you have a big powerful amplifier, you’ll need a really massive step-down transformer to power it and amplifiers are probably the least well-suited to use with step down transformers. For low powered equipment like turntables and preamps, a small step-down transformer will be fine.

Note the 100V rated equipment is not the same as 110V or 120V rated equipment. They are not interchangeable and require a dedicated step-down transformer that delivers the correct voltage. These are available, just make sure you know which one you need, indicated on the placard on the back panel of your equipment.