Based on GSMArena measurements, it seems if I do some audio hacks for Galaxy S II, I'll call it.. "audio hacks" but not Voodoo sound. IMD+Noise levels measured here are anything but good, its far worse than the stock Galaxy S badly configured. And the HP amp measured, looks .. really bad. You can forget about the shape of the frequency response, its a GSMArena measurement procedure flaw, not an equalizer or something (i'll confirm that later). I'll make other measurements and listening tests after receiving mine in a about a week but. this Yamaha audio hardware seems it's just not playing in the same league as Wolfson's.
Well no development from me about Galaxy S II audio. Maybe other people will try a few things.
This hardware is too limited for me, both in its performance and room for improvement − more or less inexistent.
I hope that reporting the full details about Galaxy S II audio will motivate Samsung to take it more seriously for the next device. They were very aware about Voodoo sound because I talked & exchanged mails with the audio engineers in Korea, and also Voodoo sound is very popular here.
I saw they did many things correctly in their software implementation, re-using some of the principles I use but unfortunately something went wrong in the process, I think probably in the hardware part on Yamaha's side. They're not so experienced building mobile codecs.