Actually coming from the dt1350 I also found the 1R sounds muffled initially but after lot of hours with it and did the dynamat mod on it then I'm getting used to it and enjoy it more ever since. Then I decided to sell my dt1350 and hd25 ii and kept the modded 1R till now.
And without the mod? :-D
I am no modder at all... My notion of modding is to f*** something... :-D