@stuartk
i have had all three (190, 390, 590), along with an h20 power amp, but that is an aside
to me, used as an amplifier only (no dac) through the rca or xlr inputs the 190 and 590 have a similar amount of high treble energy, the 390 is ever slightly smoothed over up top and in the upper mids -- overall i would say the 390 sounds the ’warmest’ even though they all obviously provide a close family resemblance in sonic presentation - the differences here are less than, for instance, plugging in a pass int-60, which provides even more midrange warmth and tube like 'wooliness'
depending on the speaker being driven the 190 may have a touch less low end grip and can sound a little leaner, but this is very speaker dependent and this would be heard on quite a difficult, reactive low impedance speaker (which the maggie is not)
i kept the 390 as it has the better internal dac than the 190, decodes mqa, and with my maggies i don’t need that touch of treble energy the 590 provides... and the 2 grand price difference is well applied elsewhere