The best replacement for firebox is audiobox.

The best alternatives to firebox are rated as following:
★★★★★  audiobox
★★★★  bushbox
★★★★  firestudio
★★★★  sonicwall
★★★  mbox
★★★  emberlit
★★★  honey stove
★★  saffire
★★  firepod
★★  duet
★★  firestudio mobile
★  fireplace
★  masonry
★  firewire 410
★  focusrite saffire
★  m-audio 410
  solo stove
  inspire
  fireplace insert
  mbox 2

Your alternative for firebox is not listed? Suggest!
Speaking about firebox, one probably shouldn't forget about gas logs.

Other search terms related to firebox and their ratings are:
★★★★★ gas logs
★★ mantel
You have in mind a companion for firebox and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of firebox in all years. Click on graph for more.
firebox
audiobox
bushbox