Audioengine B1 questions

I have and like my Audioengine B1, which is connected to a preamp and with which I stream music from my desktop Mac.  Two questions:

- If I wanted to bypass the Audioengine B1's DAC and use a separate DAC, where in the food chain should it go?  I assume the answer is that I would connect it to the B1 using a Toslink cable, but what if it were instead connected to the MAC?

- I leave my solid state components on between listening sessions.  I have noticed that with the B1, this sometimes seems to result in an impaired signal/sound - static, jitters etc.  I can solve this by unpluggiing the B1 and powering back on, but is this normal?  Am I better off turning the thing off in between sessions? 

Thanks.