I had 2 questions. The first (about the pairing dropping) was answered by radebe at the following post Muso Gen 1, Can I use Google Assistant? (All you have to do is say “Hey Google, connect” and your Home Mini will re-establish the connection). Thanks radebe.
The second is a volume thing. When it does connect, the volume through the Qb is very low. Obviously, I can whack the volume up on the Qb, but if I forget to turn it down at the end of the session, then it is deafening (and possibly damaging to the device itself) when I use a different source. I have increased the volume on the Home Mini up to 70% but that already makes her too loud and I wouldn’t want to go any higher.
Sadly I haven’t found a solution to this problem. Google really needs to implement separate volume controls for media playback and the assistant’s voice itself and there is plenty of frustration regarding this issue over on the Google Home forums. It’s worth noting that this a big problem even when listening directly on the Google device speaker. If you want quiet background music then you can’t hear your assistant speak. If you want loud music then your assistant shouts the house down.
Until they sort that, I’ve found the best compromise is to set the Google Home to a volume of 70%. If you bump the Qb’s volume up to compensate then an accidental jump back to a “full volume” source won’t be so loud that it damages the Qb.
If 70% is too loud for your assistant’s voice under normal circumstances then you could set up a routine that changes the volume to 70% and then connects to the Qb from a single command.