u can actualli mix a passive pickup with an emg active pickup tho many ppl dont do that and those who do usually add up the emg pa-2 to the passive pickup.
how do i know? cuz im using an active emg81 wif my stock passive pickup on my neck. did not get the emgpa-2 tho. this causes my middle pickup switch to be totally overpowered by the emg and thus, the middle switch sounds like my emg bridge pickup. haha. not like i ever use the middle pickup switch anyway, so no biggie for me there.
more info stolen from the emg website....
Can I mix EMG's with passive pickups?
It is possible to mix EMG's with passive pickups. There are three possible wiring configurations; one is better than the other two.
Use the high impedance (250K-500K) volume and tone controls. The problem is that the high impedance controls act more like a switch to the EMG's. The passive pickups, however, will work fine. If you have a guitar with two pickups and two volume pots, with a three-way switch, there is another alternative. Use the 25K pots for the EMG, and the 250K pots for the passive pickup. This way you can use one or the other with no adverse affects, but with the switch in the middle position the passive pickup will have reduced gain and response.
Use the low-impedance (25K) volume and tone controls provided with the EMG's. The problem here is that the passive pickups will suffer a reduction in gain and loss of high-frequency response.
This is the best alternative. Install an EMG-PA-2 on the passive pickups. There are two benefits to doing this. With the trimpot on the PA-2, you can adjust the gain of the passive pickups to match the EMG's. The PA-2 acts as an impedance matching device so you can use the low-impedance EMG controls (25K) without affecting the tone of the passive pickups. You will also be able to use other EMG accessory circuits such as the SPC, RPC, EXB, EXG, etc. For this application, we recommend ordering the PA-2 without the switch for easy installation on the inside of a guitar.