You obviously know what you want which is a good thing. Seems like you got everything covered with K701 + e12. It's true that you gain and lose some with the anniversary pads and I'm not sure if they can provide you enough bass. You could read the review from MLE's gaming headphone guide if that helps. Another option would be to get X1, but like you said you don't need more headphones and after K701 you'd lose some details with X1 and I'm not sure if you'd like those cans after all.
I'd like to try the aniversary pads in the future, from what i've heard the q701, k701 and k702 all use the same drivers, so any sonic differences come from the pads- so that's interesting
I read MLE's guide, it's what made me get the k701's- after getting them I went 38-2 in call of duty, so I know what he means when he says 'aural wallhack', he rates the X1's pretty highly too, so might try them some time too. So if I got the x1 and loved them (and didn't need the bassboost eq) I would still have the e12 as a portable amp set up, and as someone already said the T1 dac is great but the amp not so much, so even if I got sennheiser 650's, or the x1's i'd still probably run them through the aune/fiio combo (as the fiio is a great amp, it's their flagship product, and it's obvious they're very proud of it)
So I think keeping the fiio e12, and the aune t1 is the best course of action, keep the 701's for gaming and maybe in the future i'll get different headphones, might actually opt for the m50's to replace my k81's as my travel headphones
I will look into the amperex OG- thanks
it was only like £10 more, no big deal
well it wowed me out the box, if another tube is even better, then maybe i'll try that