There is an important difference between direct inputs and main amp inputs, unfortunately - main amp inputs allow you to connect directly to the internal amp sections, while "direct inputs" typically refer to the multuchannel analog input used for DVD-Audio, SACD, or any other analog audio source. Unfortunatwly, from looking at the rear panel of the HK 635 , the 8 channel input available here is not a main amp input. The only way to use an ICBM with a receiver like the 635 is to have a separate amp.