The common use of toroidal mains transformers in audio equipment has solved a great many problems but in doing so, has created others.

One such problem is because the toroid uses a much smaller magnetic core, the high inrush current at power up is liable to blow any mains fuse fitted.

A solution would be to up-rate the mains fuse fitted to the equipment but these are less likely to ‘blow’ under fault conditions and more damage may result.

The SSM2 addresses these problems completely automatically: