The unit you tried was just configured for use with Benchmark DACs having older software. When the DAC has current software, you can scroll through all four inputs on the HPA4.
Did you mean the HPA4 has latest current software instead of DAC3?
It's weird if I need to have a DAC3 in order to scroll through the inputs of HPA4.
So instead of scrolling, can we have direct input selection on any remote codes? Such as Logitech Harmony. I expect this would be a very easy change on the HPA4/LA4 software ?