Question about miner difficulty

[Kulturnilpferd]

Hey there,
I have 4 Scrypt Miners with approx 4.2Mhash each. The best difficulty for each miner is about 512 for my preferred pool. But is the difficulty on pools to set per device (d=512) or because I have 4 of them i must set it to  4x512 (d=2048)? I am confused...

[miner29]

Should be d=512 they work separately.

But more importantly have you considered that all 4 only earn $0.02 per day combined BEFORE electricity.

Why bother?

[Kulturnilpferd]

Awesome, thanks.
Just a hobby, I am mining small coins with low difficulty to get a huge ammount of them and didn't have the money to pay a huge electricity bill. Yes of course I could buy them but some altcoins are not on exchange.