So it depends if you count Pre-Season games or not to how many different stadiums we have played at against A-league opposition.
All Grounds Phoenix have played at:
WestpacStadium - Wellington
AMI Stadium - Christchurch (previously Lancaster Park)
Ami Stadium - Christchurch (Yes we played at two different AMI stadiums, this one was previously Rugby League Park)
Baypark Stadium - Mt Maunganui
Eden Park - Auckland
FMG Stadium - Hamilton
FMG Stadium - Palmerston North (Arena Manawatu)
Forsyth Barr Stadium - Dunedin
Hutt Rec - Lower Hutt
McLean Park - Napier
Mt Smart Stadium - Auckland
QBE Stadium - Auckland
QEII Park - Christchurch
Queenstown Events Centre - Queenstown
Trafalgar Park - Nelson
Yarrow Stadium - New Plymouth (Up coming game)
Grounds that have been competition matches:
Westpac Stadium - Wellington
AMI Stadium - Christchurch (previously Lancaster Park)
AMI Stadium - Christchurch (previously Rugby League Park)
Eden Park - Auckland
FMG Stadium - Hamilton
FMG Stadium - Palmerston North (Arena Manawatu)
Forsyth Barr Stadium - Dunedin
Hutt Rec - Lower Hutt
McLean Park - Napier
Mt Smart Stadium - Auckland
QBE Stadium - Auckland
Edited to add these grounds are only games Nix have played against other A-league teams.