An iso tranny also presents an inductive and capacitive load, when shielded, which should sound familiar with passive XO's. They can eliminate DC offset but aren't fond of it and can hum in protest.
The general rule of sizing, in our case, is that an iso tranny should be rated for double the maximum draw of the electronics to prevent saturation. They do not, or should not, provide ground isolation because, by code, the ground should be continuous. However, they do provide common mode (line to ground) filtration. Normal mode (line to neutral) noise is transferred through, to some degree, but most power supplies handle that in the rectifying process.
They are best used independantly as in one for CDP, one for preamp, etc. They are a defacto standard in hospitals and many industrial/laboratory applications where they prevent noise from going back into the line. Step-down transformers are common in all commercial buildings and have dual purpose.
The difference between toroidal and EI-core is mostly packaging. Toroids are less prone to mechanical hum but are not quite as effective as a filter.
The general rule of sizing, in our case, is that an iso tranny should be rated for double the maximum draw of the electronics to prevent saturation. They do not, or should not, provide ground isolation because, by code, the ground should be continuous. However, they do provide common mode (line to ground) filtration. Normal mode (line to neutral) noise is transferred through, to some degree, but most power supplies handle that in the rectifying process.
They are best used independantly as in one for CDP, one for preamp, etc. They are a defacto standard in hospitals and many industrial/laboratory applications where they prevent noise from going back into the line. Step-down transformers are common in all commercial buildings and have dual purpose.
The difference between toroidal and EI-core is mostly packaging. Toroids are less prone to mechanical hum but are not quite as effective as a filter.