Bass on 10 on the PMM, damn.
If you have Treble on 7, Middle on 8, Presence on 10 and additionally activated both mode switches Brute and Edge on the Pure Metal Machine, then the lows inevitably fade somewhat into the background and require in this extreme case to set Bass to 10
Since in my circuits the Treble & Middle controls increase enormously in their effect from position 5 onwards, I have so far only experienced such extreme settings with additional the both mode switches Brute & Edge activated with people who have already lost considerable hearing.
Of course it also depends on the guitar used, the speaker cabinet and also on personal preferences, how someone sets the controls of his amp.
Here setting examples for some of the the most brutal metal sound ever, all mode switches disabled, set by people who came for checking my amps:
The cab left is loaded with Celestion G12M Blackbacks from 1977, the cab right is loaded with Celestion G12T-75 from 1988
With the 2-button footswitch I can switch each of the two amps to each of the two cabs, whereby the unselected amp is switched to a dummy load.