Hey Kagami volume controls

[Atarian]

Hi! I'm new to these forums.

I just got an Hey! Kagami Pachislo machine, it uses the Yamaha YDA 181-T amplifier chipset, and as far as I can tell there are two of them running at 2x 30w.
I've located the speaker wires to the front connected to these two chips, a total of four speakers. There is also a sub, but it's hard to find.
But I am guessing that the sub is running on the same type of amplifier chip at 1x 50w. Hench the sub isn't very loud but the top speakers are.
I mean... loud, as in I already have tinnitus but I might give my neighbors tinnitus aswell :-P

So I'm looking to splice in two stereo L-pads, but I'm not entirely sure which ones I should get?
(Sorry I couldn't upload a picture, because I'm a new member?)

EDIT: Hrhrm... Alternative finding a way to set default volume.
There are digital volume controls on this machine, but as soon as an alarm goes off or the player leave the game the volume resets to super high.