if you have noise problems originating from the AC line, then you want an isolation transformer - a box about the size of an amp
nobody regulates what people call things, so...
cheaper used ones can be found eBay tho you may need an electrician to wire it in
if you have noise problems they usually do NOT originate from the AC line... many DACs are overly sensitive to noise from their own transformer (wall wart) or wires from it, and some make their own low inductance wires for that
other problems often arise from improper grounding, fluorescent light bulbs and even the transformers for LEDs
imagined sources are also common ;]
nobody regulates what people call things, so...
cheaper used ones can be found eBay tho you may need an electrician to wire it in
if you have noise problems they usually do NOT originate from the AC line... many DACs are overly sensitive to noise from their own transformer (wall wart) or wires from it, and some make their own low inductance wires for that
other problems often arise from improper grounding, fluorescent light bulbs and even the transformers for LEDs
imagined sources are also common ;]