Short for Measurement Lab, the open-source M-Lab test was developed by a collection of computer ... of only up to 700Mbps. You'll need to turn elsewhere if you're trying to speed-test a gigabit ...
If you're not prepared to pay up: $350 is a lot of money for speakers, although it has to be said, not a huge amount for reference units. Still, for regular usage that's quite a bit to spend.