erik,
if ‘bizarre’ does not mean that your roof hovers about 60 feet above your flat - i’d really try everything possible to install the pi and dongle as near as possible to the antenna. if there is no way the fa-dongle is not a good choice because amplification should be next to antenna - especially if you have a long cable run. so again - use the uputronics filter/amp at least there where you connect the two antenna cables. you find my installation here.
cheers
tom