Problem and question.

In your application, I would say, no. You have simplified the signal path. 

as long as you’re happy with the sonic performance, dynamics, and sound stage…

The shutdown sounds like it might be complicated to troubleshoot further. 

On bypassing the preamp: You're probably not missing much, maybe gaining something. If the Bluesound's output voltage is sufficient to drive your tube amps to satisfying levels, and its output impedance is low relative to your amps' input impedance, you're fine. A quality preamp can add body and bloom but also noise and coloration. (I tried a high quality autoformer once and it was too lifeless.) If the Bluesound sounds fine to you, probably is fine.