The most versatile and user friendly E-Stim control unit available today. If you want More Power, More Control, and more fun, then the 2B is the one you want.
This is a fantastic writeup of many popular electrode positions. Personally I like triphase #1 the best. If you haven't experienced an HFO yet, I'd recommend using the continuous mode and tune in the right frequency that feels the best. Don't know how much estim experience you have had but I think 75% of an orgasm comes from being mentally aroused, therefore watching some good porn and taking your concentration away from finding the best mode and setup will help you achieve results more quickly.
With the electrodes you describe (both with two inputs), there's no right or wrong way to connect them. If you connect one to channel A and one to channel B, that's probably the most traditional way to do it. A lot of audio tracks seem to be created on the assumption that channel A (or the left channel on some boxes) will be connected to electrodes stimulating the cock, and channel B (or the right channel) will be connected to electrodes stimulating the anus or base of the cock. So in that case, you'd probably be thinking of channel A for the helmet electrode and channel B for the plug. However, there's no reason why you shouldn't swap them onto the other channels and see if you like that effect. With some modes there'll probably be no discernable difference.
You could try connecting each channel to both electrodes. However, the arrangement of the contact surfaces on the plug will have some influence on how successful another arrangement might be. If they're side by side, then you won't get much difference between when channel A is live and when channel B is live. You may also get sensations that are too strong for you when they're both live at the same time. If, however, the contact surfaces on the plug are "top and bottom" (i.e. one at the inserted end and one at the sphincter), then you may get a certain amount of difference as the two channels may stimulate slightly different areas.
My recommendation is to get a conductive rubber loop. That would give you the option to use it at the base of your cock or round your scrotum and open up a lot more possibilities. You could then also create a triphase effect by connecting one of the leads from channel A and one of the plugs from channel B to each end of it, connecting the other leads to the helmet and plug electrodes, which is basically the triphase arrangement in the guide mentioned by rjkstim.
