I find Sony MDR 1R to be a very detailed headphone,everything sounds clear and well defined to my ears.All the sounds,from instruments to voices etc,have good detail and start and fade very smoothly and naturally,at least that's how I find them.I believe that the lack of detail you heard,was due to the smooth,non emphasized higher frequensies.But the detail is on high level.Detail is not only in the higher frequensies,although you can get the impression of a clearer and airier sound if treble is a bit more emphasized.
In my opinion and to my own ears,the MDR 1R are very nice headphones for lower volume listening at a quiet place,for example,I'm really enjoying listening to them at bed before sleeping at night.
The smooth,grain free but also detailed sound,along with the really nice imaging depth and position of sounds,makes low volume listening quite attractive and somewhat magical.Also,when listening at lower volumes,I don't find the slightly colored/empasized mids to be fatiguing,as it happens to me when listening to higher volumes sometimes.I would go as far as to say that maybe this kind of midrange also helps sound to be lush and sweet when listening to low volumes,and it helps creating a nice atmosphere.
My only problem now is that in higher volumes,I sometimes don't like the midrange so much,and I prefer shure srh 840 when I want to listen to music in higher volumes.And that is a bit of problem if I want to take them outside in noisy places.But keep in my mind that it may be just me,and someone else may be ok with their sound in higher volume listening,because everybody's hearing is not the same.
If I were you I would just equlize down the mids abit around 1000Hz, try a little and it works well if you find it fatiguing. There is also some amps that got a slightly v sound that will recess the mids abit.