Just an advice on starting out.
Don't get choice paralysis.
Like really, any of these headphones are fine. It's harder when you can't audition, but really, you'll find enjoyment out of any. Probably.
The ones you've picked all have wide soundstages, some more than others, but not to the point that you should worry about it. The AKG is the widest. A bit too wide though.
If bass is important to you the beyers are your best bet.
Beyers are known to emphasize the treble. Avoid if you're sensitive.
Audio technicas are known for their upper-midrange peak. I really like it because it really makes female vocals shine. Some people find that it sounds harsh. YMMV. AD900x makes the bass not lean as shit. Still not basshead levels but I guess that's not what you're looking for.
From what I've read (never actually heard them) the 598 should be rather similar to the AT house sound, with an upper mid peak. Bass is underwhelming from what I know.
No idea about your amp, should be fine? The AKG are probably the hardest to drive out of any of them unless you're going for the 600ohm beyer models.