On FW 2.14 beta there is more than just bass and treble EQ. you can adjust several different frequencies because I think it shares some of its firmware with the X5.
I think the EQ is great on the FW 3.0 anyway so I don't use this.
This is the link with the volume mod.
Strange about your 3.21 opinion, it really shines with my Grado SR-80i