Thanks, I think I am starting to understand. If I want to experiment to see if I can improve sound or soundstage I can use amp1 with SE out and outboard amp SE in with a connector I will have to purchase. I could use the balanced out of DX200 to connect with a balanced input of an outboard amp as well with additional connectors. If I do not want an outboard amp and want to change the sound signature of the DX200 then I could try the amp3 or amp2 (which may not be able to drive the HD200 S). Just let me know if I am on the right track with my thinking.
If you attempt to use the DX200 balanced output to an external balanced amp input, you will be double-amping the signal as the DX200 balanced output has already passed through the amplifier stage and is an analog headphone output. While it is possible to use the DX200 as a digital source, it is really a waste of excellent downstream circuitry and there is no way to get a balanced digital output from the DX200.