what the world needs.

i was thinking along the same lines yesterday on the way to the studio. I retired the idea of the line amps because I would rather put the money into preamps and then use those across the outputs.

a 1:1 transformer would work well. there was a guy on the purple site who used transformers on the outputs of his lynx auroras.

Ball grid arrays, very tricky and needs a lot of patience.
I have seen how somebody reballed a BGA, it was a GPU.
Needs a hot air applicator formed for the BGA, and a stencil for applying sticky flux paste to let the balls adhere to the BGA. That's already the "special" tools for it. The stencil can be etched and the hot air applicator be formed with metal sheet. Don't know if/where you can buy them anywhere...

Patience game, especially the reballing takes a lot of time. Sticky Flux applied with the stencil on the cleaned pads, balls spreaded to adhere to them, then correct everything with precision pliers until all balls are in place, hot air carefully applied to let them flow. PCB cleaned with solder wick and usage of much flux...
Reflowing the BGA on the PCB with hot air and the BGA applicator.
Yeeees, it works, but a lot of tricky work, i would avoid it where i can.

It was fascinating to see this been done in a hobby room and not a clean room in a factory...
But really - not my cup of tea. But there are people who repair Mainboards and graphic cards, gaming consoles etc. with these techniques at home.