Here is quote from the Concerto technology -
With most amplifier designs, input impedance and gain will vary depending on whether the balanced or unbalanced inputs are used generally, unbalanced inputs will have half of the output of balanced inputs. With the Concerto Integrated Amplifier, there is no difference between balanced and unbalanced inputs, meaning that there will be no differing characteristic in sound quality and output level depending on which inputs are used both will provide the same seamless, neutral presentation.
http://www.jeffrowland.com/Docs/ConcertoIntegratedTechnology.pdf
With most amplifier designs, input impedance and gain will vary depending on whether the balanced or unbalanced inputs are used generally, unbalanced inputs will have half of the output of balanced inputs. With the Concerto Integrated Amplifier, there is no difference between balanced and unbalanced inputs, meaning that there will be no differing characteristic in sound quality and output level depending on which inputs are used both will provide the same seamless, neutral presentation.
http://www.jeffrowland.com/Docs/ConcertoIntegratedTechnology.pdf