I need a one to one audio isolation transmformer, XLR in/XLRout, that can handle line level. Does Shure make one?
Shure does not.
Lundahl Tranformers, a Swedish company, offers the model LL1584-3FX3MX that meets your requirements. It is rated for 600 ohms and has a maximum signal level of +17dBu at 50Hz. Lundahl offer a variety of other transformers with different input and output connectors.
http://www.lundahl.se U.S. agent: www.kandkaudio.com
Also, Radial Engineering makes one. It is the Ice Cube model IC-1. www.radialeng.com