Boriss
Sorry for the delay, my power was out over the weekend due to inclimate weather.
I thought the M88 drove my Maggies nicely in triode mode. I have never understood that people thought they had more power in tetrode, they just play louder (and sound more ordinary) but without the control or sense of drive IMO. So (of course) the 90 should do a nice job as well. I will concede that tetrode mode had a lighter and maybe more open quality but not my cup of tea.
The bottom line for me though, is the search for more dynamic range with Maggies, the only time I had enough was with the Innersound ESL amp but did not especially care for the other sonic qualities of that amp. All other amps had negligable differences in that area, including the difference between the M120 and M88.
best of luck
Phil