Today I went to a audiospecialist, I tested out the 750 and 900. Though I spend about 25 minutes on the 750 vs about 3 on the 900.
The Pro 750:
I thought they sounded nice, I don't have such good memory, I try to recall the best I can. I liked their sound, look and comfort. I didn't have any issue with harsh highs or siblance at all. Do note that I was running this through Phone>Arrow 3g amplifier. So perhaps the amp took care of that. I found the body of instruments lacking a bit though. I find it really annoying to not be able to know how they will sound after burn in, equalization and or modding. It makes me a bit puzzled on what to chose. I disagree with that they have a bass that makes everything bassy. It sounded loud but not bloated on bass heavy music, but when it wasn't such music it didn't. I speculate they let you hear as much bass as how it was recorded. I like that..
The Pro 900
Of course my listening time doesn't make this quite conclusive, but the difference I heard was significant. But not in a good way. They sounded a lot darker. The sound also seems to be coming from farther away, I don't know whether I like this or not (just the farther away bit). Or that it was just the recessed mids that put me off. This one was more comfortable though.
Does a modded 900 sound (SQ) significantly better then a modded (or stock) 750? Are the mids more on level with the 750 when it's modded? I don't mind spending 105 euro's more on the 900, but the difference should be significant to justify it's costs.
I'll revisit the audio shop too get a better image of their sound, I could expand on my impressions then if anyone is interested.