The best replacement for surround is surround back.

The best alternatives to surround are rated as following:
★★★★★  surround back
★★★★★  stereo
★★★  tile
★★  eyefinity
★★  focus
★  sound bar
★  stereo headphones
★  surround back for 5.1
★  5.1
★  5.1 surround
★  quantum
★  soundbar
★  samsung focus
★  front speakers
★  stereo headset
★  around
★  7.1 surround
★  dolby digital
★  virtual surround
★  stereo 3ds
  encircle
  7.1
  hd7
  aria
  lg quantum
  back
  bookshelf
  htc aria
  pro logic ii
  dts
  ceramic tile
  shower surround
  stereo xpand
  samsung captivate
  xpand
  2.1

Your alternative for surround is not listed? Suggest!
Speaking about surround, one probably shouldn't forget about seat.

Other search terms related to surround and their ratings are:
★★★★★ seat
★★ tub
You have in mind a companion for surround and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of surround in all years. Click on graph for more.
surround
surround back
stereo