Mmmm... See I don't think the treble is emphasized on the HE500, it's very balanced with the bass and mids. The D2000's do have a lot of treble energy that is emphasized more because of the "U" FR, also Grado's (most models) and AKG's KQ7XX do show siblance on recordings that really shouldn't. It may just take a little adjustment time to get used to the superior resolution. When the HE500's first came out they were constantly accused of having rolled off treble... Some still think so. Having said that, you can still have fatiguing treble even with a roll off if the peaks are there. If you take a look at a graph of the FR you will see a peak following a dip from the mids. This will pick up the middle treble and high- light certain instruments or sounds giving a welcome sharpness that would otherwise (for me) be too smooth and dare I say it.. Dull
I can't speak for the amps that you have or are getting, but I have tried 5 budget to midprice of varying power and never have I found the treble intrusive or emphasized. For me it is very sweet and revealing
Because I listen to a lot of Jazz and classical I can't have bad treble... Just can't!