gamesx mentions that the amp is not necessary:
If you can get the parts and have the ability to assemble this amp, you won't regret it. For most monitors it's not necessary, though as mentioned above some won't sync without it. If you use an upscan convertor like the XRGB-2 you'll have a very acceptable image without the amp.
http://www.gamesx.com/rgbadd/duorgb.php
I guess you guys don't know the answers to my questions then. Thanks anyway. I'll add the amp and see what I get from there.
Hm, I never noticed that (
looks like they updated that page too, looks much better!), but it's
terrible, lazy advice to just hook the pins straight from the chip to the TV/monitor and that goes for any other console unless you know the signal was properly prepared for TV/monitor output/usage and can handle the load... The DC offset (
as ApolloBoy mentioned) on the RGB pins is like 4.66 Volts and that 220 uF capacitor on the output in
the full Japanese amp circuit filters that out. Also, the transistor works in a way where the signal behind it isn't attenuated at all when you plug it into a 75 Ohm load (TV/monitor or video converter device), though this doesn't quite matter with the 6260 chip so other video signals (Luma/Composite) don't get attenuated if plugged in at the same time. Anyway, those are good things to do or have, in other words. You wanna both protect the chip and prepare a proper, independent signal for the TV/monitor to process (thesteve could better explain, but yeah!).