From reading the manual and watching some youtube videos it looks like the attenuator can be used in two ways make a loud amp quieter and make a small amp sound bigger. when using a small amp for example a princeton or a small tweed amp with a low wattage speaker could you possibly damage the speaker?
We recommend volume matching slowly when using a low-power amp with the PS-2A or PS-100.
Power off PS-2A and amp
Put PS-2A volume on zero
Connect your amp to the PS-2A and then the PS-2A to the speaker.
Turn on the PS-2A.
With the PS-2A in BYPASSyour amp is connected directly to your speaker. The signal goes right through the PS-2A. So turn up the amp to a reasonably loud setting (the loudest you want for your application).
With PS-2A volume knob at zero, turn PS-2A into OPERATE.
Now, very slowly increase the volume until you hear something.
Now put the PS-2A back into BYPASS
Get a feel for the volume level.
Keep on putting the PS-2A in and out of OPERATE and BYPASS until you have matched the volume level. This is then max. safe knob position.