This is a bigger question than you might think. The answer won't be short and I'll do my best to avoid as much technical jargon as possible.
Inorder to emulate every MAME game perfectly, your monitor must be able to support the following
x192 at 15kHz (a handful of games)
x224 at 15kHz (almost all games)
x240 at 15kHz (several games)
x384 at 25kHz (a handful of games)
x480 at 31kHz (vector games)
Most 15kHz arcade monitors were designed to display 224 lines at 15kHz. Newer ones, however, go up 240 lines at 15kHz. This means that most arcade monitors can perfectly emulate one of these two modes. Inorder to emulate both, you need to overclock / underclock your monitor. You basically need a 1kHz horizontal range, so for example, you could use 15kHz at 224 lines and 16kHz at 240 lines. This setup would enable you to run 90%-95% of all games perfectly (thats just a guess, but it should be pretty close).
Since the D9200 supports 384 lines at 25kHz, it is capable of perfectly emulating a few of more games than a regular arcade monitor. If you double the pixels for the handful of x192 modes, you end up with 384 modes running at the correct vsync as well. So, basically, depending on how you want to define perfect emulation the D9200 can also very accurately emulate x192 modes.
The last remaining vector mode, 480 lines at 31kHz, is also support by the D9200.
So basically, if you overclock / underclock a D9200 you can emulate every MAME game perfectly. If you overclock / underclock an ordinary arcade monitor you can still emulate 90%-95% of all games, which ain't that bad, if you ask me.
Wow, that was a lot shorter than I thought it would be. Anyways, I hope it helps.