As you hear there are no stupid questions, right? Well I have one that may qualify... What's the application for the optical 3.5mm IN on the Astell & Kern? It's a source so why would I want to run a signal into it? For the DAC? My apologies in advance..I'm new to this stuff.

I am new to the forum and didn't read the rules before posting and put my first post in the headphone section, my bad. So this is my second post officially...I've been into audio and music for years, but just got into portable hi-fi and its a heck of a lot of fun. I have had an all tube system...

(Edit: Sorry to put my first post in wrong place, my apologies) I am new to this headphone hobby, but into audio equipment and music for many years. This forum has been such a great source of info for me and got me pointed in (I think anyway) the right direction. I recently acquired an AK100 and...