I have mine at 1x/2.5x and I almost always find it enough.. But, I don't think I would mind having 1x/3.5x.  I usually stay on 1 unless I'm using a source other than my odac.. such as a sansa clip. At such times, I wish I had more than 2.5x on very quiet recordings.   1x/3.5x sounds pretty...

    I too think it is mostly the ears/brain adjusting to a new sound sig. 

I do this with a similar cable and or sennheiser 3.5mm to 1/4" pigtail adapter. I secure the cable/adapter to my desk with masking tape. Can't tell you how many times it has probably saved my output jack.         Hah, easy misunderstanding. 

        I thought you were joking.   I've never heard the ODAC+O2 described as having a "warm glow".   It's cool if that's the way you hear it, but I think most people describe it as pretty transparent.  

Trollololol?

Do you notice any noise or unwanted distortion with your current setup? If so, the o2 and odac would remove this problem. Do you feel the need to turn up the headphones to a louder volume? If so, yes the o2 and odac will give you a higher gain and allow you to reach higher volumes. Other...

.

I would just pay attention to the cable, it is likely the first thing to break on it.. That being said, mine is flimsy and has lasted forever. I even leave it in the car when it's hot/cold.

I really wouldn't. Magnums are really kinda fine tweaked, I don't think they are meant to be punched.. And you might have a hard time ever recovering them.. What makes you wanna punch the holes? Want more bass? Get a sealed on ears or in ear monitor.  Let the magnums be IMOO

.

.

Yup! I'm sure others will chime in with the same answer, or if I am wrong :)

Off topic, but any specific Brahms recommendations? I definitely get in the mood for some classical. 

Negative, there is a charging circuit in anything that uses rechargable batteries to prevent this from happening. At least, anything that is well designed.. Same thing goes for your phone, except there may be a circuit in the charger as well as the phone in that case. Designers anticipate this...

You can use it without batteries, but I dunno why you would want to remove the portable functionality.