Do you mean that you have the RE-600?   If you want a similar neutral sound, then the new Etymotics are worth a look, the ER4-SR and ER4-XR. The XR has a little bit of extra low frequency presence, but not too much. They are incredibly detailed, so if you're listening to ropey recordings or...

What you call passive noise cancelling is more usually referred to as isolation - I was thinking of the Etymotic HF5 which is great for this, plus it's fairly neutral with perhaps a bit more presence in the midrange. However, depending on your ears, these may lose points with the comfort.  ...

I really like the T20, but I haven't laid my hands on the IE80 recently so can't comment on that so much. One thing to consider is that the IE80 has a replaceable cable, and you can use the IE8i cable if you wanted a mic/buttons.   Another one I'd mention is the Fidue A83 which may suit you too.

We went down the road to visit B&W and spoke to the chaps who work the magic there. Take a look!  

If you've enjoyed the HD465 for so long, you might find the DT880 a bit of a shock - it's noticeably brighter-sounding and may stray into fatiguing territory for some people. The HD598 is the safer choice, although you can of course tame the highs on the DT880 using the mixer EQ.

I'm wondering why your current earphones fall out, are they earbuds (non-sealing)?   Whatever may be the case, perhaps look at something with a cable which goes over the back of the ear which will help keep them in place.   The Shure SE215 is a good one for EDM, plenty of bass and quite...

These are advertised as being suitable for ages 4 and up, have volume limiting, and they're pink! Isolation should be good too, although this is down to the girl's ears of course!   http://www.hifiheadphones.co.uk/etymotic-ety-kids-5-safe-listening-in-ear-isolating-earphones-pink.html

  Their earphones are decent, the tuning is a fairly standard consumer sound with maybe a little bit extra treble coming through.

I've enjoyed a bit of rock with an E10 in my time, the bass on them gives those heavy chords a nice weight. You might consider the E50 as well, these have a bit more midrange presence so might be more suitable if you're wanting more pronounced guitar/amp distortion, harmonics or vocals.  ...

There's a few current reviews for these (there's two on the front page at this time) so have a look - the Meze 99.   These have a powerful bass, but midrange isn't affected - they're heavy hitters and should just be within your budget -  ...

I'm assuming that you're easy about the headphones being open or closed backed, so with comfort in mind, the HD600 might be your cup of tea, or the HD650. Given your thoughts on the DT990, the new DT1770 might be worth a look too, although this might squeeze you budget if you require a DAC/amp...

I assumed it would have been mentioned in this thread, but Canjam London is your best bet, if you can wait until mid-August. There will be a whole selection there - take your Mojo and player and you're all set.

And not forgetting the week leading up to Canjam London, where there's a 5 day strike if talks don't help things. I'm glad of my motorbike!   We can't help that, but we're otherwise an easy ride down from Victoria - by the way you'll need Lancing for us, but you may as well do Brighton too.

It is likely that the tubes on the J69 are not in the audio path, they are there to look good while the audio just gets amplified using solid state components. If you have a spare half an hour, it gets a close inspection here -   https://www.youtube.com/watch?v=coSt5HWRvv4   Edit - it seems...

The Fiio amp will be OK with the M2, HD600 probably not.   Is there any reason you're looking at a closed-back headphone? I find a closed-back works well with electronic genres so that's no bad thing, but we have visitors here who may not be aware of the design differences between the two...