I have the HE-500 stock cable converted to balanced and can use the same cable as SE/Balanced from Audio GD NFB 28.
The balanced connection sound perceptibly better compared to SE, but I believe loudness plays a part (Balanced means double the power). I am not quite sure by how much I need to increase volume when using as SE so the SPL matches. Any suggestions. Example, the HE-500 is sufficiently louder at at say volume level of 105 on NFB 28 (100 is mute) where as SE it need to be around 112, but these are subjective. Any better suggestions to match the SPL? Thanks.