HI,
I recently tried ad817 in the mos 250, and it seems to work ok. Bearing in mind that I run the output mosfet pair at a quiescent curent in excess of 560ma, and also have the 390r/82r mods in place. Well in comparison to ad825 it just sounds much more 'right', more fluid, natural, the detail complements the music and is not in your face like the ad825, also the resolution on edges remains focused but is not as edgy or harsh. The most interesting aspect of it's introduction is the resolution of the system stays more constant during complex passages. I havn't tried anything faster than this opamp in the mos250 yet. The ad817 is quite suitable due to it's high but not excessive bandwidth, fast settling time and slew rate of around 300v/us. The other 2 opamps I have in mind are ths4061 with slew rate of 400v/us, but a high bandwidth of 180mhz, or ad818 which slews at around 500v/us and has a bandwidth of 120mhz or so, but I am a little weary of the chance of oscillation. The good thing with ad817, ad847 and ad818 is that they are available in standard dil style, so that adaptor sockets aren't needed.
Thanks
Raja
