Why not use ONE micro with FOUR ADC's (not a hard thing to find) that reads all four values at once, then reports the data back over ONE serial link? Without more detail about your setup I suspect you're deluding yourself about your ability to get 1mS accuracy/synchronisation too. **Edited to add**: If you can give more detail about the application there are lots of other solutions; 1ksps is easily doable through the laptop sound-card (most will do 96kHz/16-bit on 2-channels, many can manage better / more channels).