I am completely happy with my PSX hacks, and wouldn't even consider buying a keyboard encoder. (Just so that is on the record
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I used the MegaTap adapter through the parallel port (DPad Pro driver), and use 2 digital PSX controllers which gives me 2 sticks and 10 buttons. 6 buttons are for play, 2 are for coin and 2 are for 1/2P start.
I have several open buttons as well, so a pair of Digital controllers can give you up to 10 buttons and a stick per controller. I just didn't need them for the games I am interested in. Junior gets a little upset sometimes when he tries to go for a combo on SF or whatever, but too bad. It's Dad's game, and if he wants to make a better one, I'll give him a hand with the saw
Anyways, all THAT said, the Megatap will let you use 4 controllers, and I have used 2 analog controlers on it successfully many times when I just wanted a pad for a PC game.
Currently, I am laying out flight controls for myself and will use PS analog controllers for stick, dual throttle and rudder pedals. It will all run through the Megatap adapter.
BTW, total cost for the pair of digital controllers and the 4-way adapter to cannibalize was less than 30 bucks. Total for the whole thing, wire, connectors, box for the board, etc, was probably less than 40. Timewise, it probably takes longer than an encoder, but I have more time than money, and have no need for that many controls.
This, of course, is only my opnion, I am certain that there are others available
Feel free to email if you have any questions, or want to see pics of my crappy soldering job.
K