not again

[sighd]

Why does my Laney a100 series11 hum in the effects loop when my pedal are using 110 power supplies

[Enzo]

Does your FX pedal hum if you connect it between the guitar and the regular input jacks while using 110v supply?

[The Dude]

Without more info, these are some "stabs"

1) Your effects loop is line level and you are running instrument level pedals. (also would be an impedance mismatch)
2) You have the wrong power supply for your pedals. Many pedals (including and especially Boss) require a very well filtered power supply. There's not much filtering in the pedal itself. They don't play well with some "off the shelf" power supplies.

Can you tell us what pedals you are trying to use and if available what the specs are on the loop in the amp?

Edit: Just looked, that amp does have a line level loop. In other words, it's not built to work with instrument level pedals.