The drivers are 30 cents a channel, so that's not really to crazy.
An op-amp is going to be slew rate limited, you will spend more time doing the switch than you would like to. It's also going to be quite slow when driven in and out of saturation at both ends. I'd avoid the op amp.
The 339 comparator is simply an open collector driver. You have a pull up resistor doing the turn on. They have a very limited current capability. You can only make the resistor just so small. That gets you into the same slow transition issue.
These modern FET's have a *lot* of input capacitance. I've used bypass caps that have less capacitance than many of them have. Since part of it is miller effect enhanced, things can get mighty slow with a low power drive. You don't have to spend much time at half voltage / half current to put quite a bit of energy into the FET. Do a few thousand transitions a second and you may need a pretty good heat sink (which I believe we are trying to avoid ...).
An op-amp is going to be slew rate limited, you will spend more time doing the switch than you would like to. It's also going to be quite slow when driven in and out of saturation at both ends. I'd avoid the op amp.
The 339 comparator is simply an open collector driver. You have a pull up resistor doing the turn on. They have a very limited current capability. You can only make the resistor just so small. That gets you into the same slow transition issue.
These modern FET's have a *lot* of input capacitance. I've used bypass caps that have less capacitance than many of them have. Since part of it is miller effect enhanced, things can get mighty slow with a low power drive. You don't have to spend much time at half voltage / half current to put quite a bit of energy into the FET. Do a few thousand transitions a second and you may need a pretty good heat sink (which I believe we are trying to avoid ...).