"If you need more inputs, you can get the optional Ext90 extension using the compatible connector".- AmirWhat digital input?
Consider it as a straight wire with volume control , plus a headphone amp on the side.
Preamp is a misnomer. In my book, a preamp would at min. have input switching facilities, if nothing else.
For digital Ins, Topping sells DACs as well. It's a modular system based on separate components, You configure it as you wish. You are allowed to not like what they propose, they also have Dacs and Amps combined for you. Every one happy.