spikes all the way, but depending on how sharp they are and speaker weight, they may actually sink into the plywood floor and cause the speakers to not be level. In those cases, it's best to use spikes and floor saver metal disks under the carpet that contain the sharp spikes or adjust the spikes length to compensate for the amout it sinks into the plywood. At 80 lbs. per speaker you may get away without the floor saver disks as the spikes may not penetrate that far into the plywood. YMMV.
