Is it possible to build a LA2/3 and incorporate a switchable high-pass filter into the LA2/3 design? Like 40-60-80-100-120-400 Hz
Just like on the SSL mod...
Wire it into the T4. In series with the EL panel. More (smaller) capacitance. If you want to spare the unit from drilling, just make a short octal extension and switch small caps in the feed to teh EL panel, that'll do it.