This is exactly the way I feel with my Grado RS1i and my Beyer T1.Those are both special phones(and WAY more expensive) but my next trip abroad I will bring only my HD 650.
After owning both HD 800 and LCD2, my HD 650 finally arrived today. My first impression running off the Phoenix single ended (way worse than balanced) is already positive. Very good build quality. Not on HD 800 level of course, but I don´t feel bad about dropping these! Very lightweight and the most comfortable headphones I´ve ever tried. The HD 800 is also very comfortable, but it´s a little bit too big for me (still very nice though). The LCD-2 isn´t in the same league as either one comfort wise (they feel like wearing a coca cola bottle on your head weight wise).
As for the sound, well, I think the Sennheiser leaflet describes them well. I don´t hear a veil at all, sounds very natural, yet towards the easy listening direction. Beautiful treble. Not overdone, but not underdone (LCD2) either! This is what I´ve been looking for. Sounds good with all genres I´ve tried so far, but I have to give a special shoutout for the beautiful warm midrange. Are these neutral? Not really (neither are the LCD2 if you ask me, and HD 800 almost if it weren´t for the overdone treble). But they are tuned towards feeling the music, not analysing it! For once I actually agree with the marketing talk. The HD 650 are pretty much the Sennheiser "musical" line.
Even at this early stage (started burning them in now), I can already say I will be keeping these. There is nothing at all that annoys me in the sound signature - but no I don´t mean that they are perfect. Less detail than LCD2 and HD 800, but if I had to choose just one of the three and they´d all be the same price, I´d select this one. Looks like I found my first keeper headphones. This is what I wanted when I bought the LCD-2. The tonality is in the same direction, but not overdone and most importantly the soundstage is way beyond what the LCD2 can do. So is the comfort (which is extremely important, almost as important as the sound). Will add a more neutral can to my collection later though, something treble happy to use for classical etc.
Oh and PS: Audio-gd house sound is FANTASTIC with these. The Phoenix and REF7 have fantastic synergy with these. Highly recommended for anyone who finds overdone treble annoying, but isn´t willing to start wearing a brick / doesn´t like the ortho limited soundstage :)