Nice, keep the posts coming!
I would also like to hear how you owners feel about the passive tone knob! I'm thinking it makes a nice addition to a sculped active sound, especially with those filters, dialing in some passive tone to further shape the tone. I'm guessing that it is best used subtly?

Me want one! NOW!
I don't have the passive tone knob on mine. As I said, I tend to treat the ACG as a "supercharged" version of the passive tone, so I honestly don't know how much use an additional passive tone knob would be. After all, the passive tone simply cuts frequencies above a certain cutoff frequency (based on the capacitor value), and you've already got a LPF doing the same thing in a more flexible way.
Maybe someone who has an ACG with the passive tone can chime in about how they use it?
I was searching for something else and found this thread. It's from back in January but I thought I'd comment for anyone that is interested.
I had experience with the EQ02 from having one in my (since departed) Stambaugh fretless. So I had a good idea of what to expect from the EQ01. And when Alan mentioned the new EQ03 being available I thought it would be cool to have the added active/passive mode, tone control and mid boosts but I had no idea exactly how useful they'd all be,
especially the tone control.
Sure, you can throw the bass into passive mode and have simplified controls of volume, balance and tone. It lets you hear exactly what the bass sounds like without any EQ and makes it easy to cop more of a vintage vibe.
But in active mode it also interacts in an incredibly important way with the LPF and HPF stacks. The LPF have a range of 7kHz (wide open) down to 70 Hz (all the way closed) with an overshoot peak boost of up to 10 dB and the HPF is a shelving control from 1.5 kHz to 10 kHz with a ton of boost on tap (+18 dB).
As you close the LPF it starts cutting treble and then high mids (and eventually low mids and high bass if you keep going) but the HPF stack can add some of these cut frequencies back in.
The problem is that because it's a shelving control it can get harsh quickly when boosted. The tone control allows you to roll off that top end to keep a full but smooth sound.
On my old EQ02 I rarely boosted the HPF much, if at all. With my new bass I boost it all the time and take the edge off with the tone control. It is (IMO) a HUGE upgrade to the preamp, making it far more versatile and useful. The mid boosts are a stroke of genius too, especially now that I've tinkered with them and have them set to my taste.
I've had a number of very good preamps in my basses over the yeasr (Audere, Pope, Bartolini, Glockenklang, Aguilar, 2 & 3 band Stingray) and a few others that I wasn't as fond of and while I wouldn't hesitate to use or recommend any of them, the ACG EQ03K is far and away my favorite preamp I've ever used.
There is a definite learning curve to it, but the tonal rewards are so worth the time spent getting comfortable with it.