I too have a balanced unit but it doesn't sound cleaner or stronger either way if the signal is already clean and amp is powerful enough for the phone used.
My point was in the case of DX90, which is already clean any noise you will further reduce by going balance doesn't merit the cost and risk imo.
Fair enough, in my case I would not mind having a balance out to my balance in amp but that just my preference, like you though price is definitively going to be an issue as I don't want to spend an arm and a leg getting to that state. I have an amp I consider better than the DX90 so feeding it the dac outputs only makes sense to me.
I also like the slow roll-off. It sound more natural to me than the sharp roll off which sound clinically clean and stripped of micro details.
That was a feature I was really looking forward to see in the DX50 but really glad they eventually incorporated it to the DX90, the slow roll-off is also my preference as it still lets the harmonics at the edge coming through and yet cut it off the undesired high and lower frequencies although it's getting hard to get them as the DACs and amps have gotten way better at low noise floors nowadays.