Transformers are great problem solvers, but there are a bunch of crappy ones on the market. Ebtech comes to mind as one of the suspect ones. A cheap
transformer will not handle high audio levels without saturating the core, especially at low frequencies. The result is
distortion. If the manufacturer does not spec the maximum
level (in dBu) and the
distortion at that
level (<1%) , assume it's poor.
Balanced line level can easily reach peaks of +18 dBu to +24 dBu.
Looking at ART's product on their web site, to their credit, they do include the max
level/
distortion specs, and they look decent. They claim <0.05% at 24 dBu, at 100 Hz. It's nice to see that, and I would say go for it for $60.
Applied Research & Technology: ARTcessories™
THE renowned audio
transformer company is Jensen Transformers. I totally trust their products and use many of them, and they always sound great when they are applied properly. They are not inexpensive, however.
JENSEN TRANSFORMERS, INC. - ISO-MAX® Audio Isolator Products
Generally speaking, put the
transformer next to the input, not the output. Most transformers are not great at driving the
capacitance of a long piece of cable, unless they are specifically designed to do so.