Could i use a volume pedal instead of power attenuator? Does it work the same or does the volume pedal lower the gain too?
The volume pedal lowers the overall volume of the amp rather than lowering the power, so no, it does not work the same.

It helps if you want things to be quieter, but it won't give you power tube breakup.
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Power scaling is much bettterrr!

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A volume pedal is just like turning down the volume knob on your guitar.

An attenuator actually increases the load on the amp, as if it were running a whole bunch of big, powerful, but silent guitar cabs.

It's useful for people who want their amp to sound like it's being pushed, but without the volume.