Ok here's a funny story. Take it with as many grains of salt as you wish but it worked perfectly for me.
I spent a lot of time yesterday trying to fine tune the treble with EQ and tip rolling exactly where I wanted it but it just wouldn't work - the highs would either be too fatiguing or lose the sparkle. Then on a whim I took a piece of tissue paper (Scotties 2-ply facial tissue to be exact) and fitted it over the nozzle with a wide bore tip (the wider tube made the fit over the nozzle easier) and the highs are now
spectacular for me without EQ. I've been listening for several hours now and there is no treble fatigue but all the detail and sparkle is there. Very high-tech solution indeed but worked well.