Topping Ext90 Input Extender with 3 Balanced inputs and 1 Analog Input for Topping Pre90 A90 DiscreteExt90 is an input extender with three balanced inputs and one analog input. Topping's products with an aviation connector can be connected to Ext90 to obtain more input interfaces. We believe Ext90 will bring you HIFI music experience and fun! The Ext90 is a device that pairs exclusively with the Topping Pre90 and A90 Discrete, allowing the latter to take advantage of more inputs. Thus, by combining the devices, you have two single ended RCA inputs