Thanks, Matt. Somehow I guessed I was not the only one with loads of "spare parts" laying about :-)

The Dragonfly output is 1/8 inch.

I thought the noise issues with 1/8 inch outputs would be solved if the signal from the laptop was converted to USB via the Dragonfly, then routed to the 1/8 inch auxiliary in jack on the powered speaker. Is this incorrect?

Do you think there would be a significant sound quality or noise reduction difference having the BIAB signal going into an XLR port (with the Mackie) as opposed to going into the 1/8 inch aux in port (with the Dragonfly)? I could easily switch the guitar to the 1/4” jack and put the BIAB signal into one of the XLR ports.