First, connect two of the 16 ohm speakers in series. This will give you a total resistance of 32 ohms.
Next, connect the remaining two 16 ohm speakers in parallel with the first two. This will give you a total resistance of 8 ohms.
The final configuration will look like this:
```
+-------------+
| speaker 1 |
+-------------+
| speaker 2 |
+-------------+
+-------------+
| speaker 3 |
+-------------+
| speaker 4 |
+-------------+
```
The positive terminals of the speakers are connected together, and the negative terminals are connected together.
This configuration will present an 8 ohm load to the amplifier, which is what is required for most amplifiers.