Not sure this is much help Thomas, but i use an upgraded Bushmaster II with the Capella, and have to say it’s a fantastic combo.
Previous to that i just used the Bushmaster for headphone duties, but after adding the Capella it stepped the game up a great deal.
The extra functions on the Capella made all the difference for me and brought out the best in my Audioquest Nightowl phones.
I can’t really explain the difference without sounding like a tit, but for me it worked well.
I also use a small aux car battery to power my set up and to me it’s way better than the supplied wall warts.
Might be worth sending Stan a PM on here if you need to know something, he’s a proper good guy and couldn’t be more helpful.