Problem and question.

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.

Friend

Very sorry to hear about the fuse situation.  It sounds like a thermal issue or perhaps a short.  At any rate,  Source direct to Amplifier brings many sonic gains - but a top tier Preamplifier will make a difference.  If you are enjoying the presentation right now - all is well.  But one word of warning - don’t go poking around trying top tier Preamplifiers.  Once you get pulled in by one - you will be spending money.

Thanks, everybody. I’ll use what I have and go directly into the tube amps. 

@studio1 Haha, I’ll stay away from the high end preamps. Thanks!