Because the HD650 has a midbass hump, you need to do some serious EQ compensation for the HD650 to get clear results. The midbass can veil the sub-bass, mids and treble is what I have found. I have owned one for many years. The Q701 (I don't own these but my friend does) has higher quality sub-bass and picking out the individual notes is easier. I never got the "lack of bass" criticism of the Q701/K701. It's there and very audible. Personally they're too thin for my liking.
What's your beef with the AKG Q701? You don't like a headphone, you don't need to say that it's flawed in every thread.
He loves to bash the Q701! That's OK. I do that with the HD-600 sometimes despite using it a lot. Even the HD-598 sometimes.
Q701 is quite an impressive headphone. I had a love/hate thing with the K702 and I do believe many people who hated the K702 might like the Q701. Maybe some Q701s have "special" drivers and sound different than other Q701s. One would need to try out a dozen pairs to know for sure. AKG does claim the K702 is open and the Q701 is "semi-open". I'm using a Q701 with a very neutral amp/dac and it's still warm and full sounding. The mids on my old K702 were thin and almost recessed sounding (except for upper mids). Had this weird peak in the treble that drove my ears bonkers.
Vocals only sound distant if it's that way in the recording. The Q701 is very accurate to how things are recorded. I will say that some vocals are more forward sounding on my DJ100 and HD-580 though. The Q701 can sound thin or warm and full sounding depending on the recording. It's quite interesting. Unlike say the HD-650, it won't make very warm recordings into a muffled and congested mess. You know, with the wrong recording I can get the Q701 to sound like the AD700 Yeah..there are some recordings in my collection that are that bad. Ugh. Sometimes I think people blame the headphone when it's the recordings fault!
Right now i'm using the Q701 with a Canare DIY cable and it sounds pretty similar to the HD-598/K601, but much clearer and a larger soundstage. Right now I think if the Q701 was any warmer it's sound would be ruined!
I highly doubt anyone has claimed the Q701 is fatiguing. It's treble for me has always been really smooth. It's only bad with maybe a few of my garbage tracks. When underamped the Q701 can be a bit harsh and thin.