With my Ketron SD5, I have everything flat! In fact there is no internal e.q. on the SD5, except for the mic. The two channels on my mixer are flat and the Bose is on preset 00.
When I use the PSR S900, I use internal e.q. on the keyboard. You have to add sizzle to the drums, bottom to everything and try not to muddy up the mids.
Dikki, I see a LOT of groups doing what you describe. Also, they usually don't listen to me if I try to explain they are double-boosting or double-cutting, so I generally don't mention it.
DonM