@Shockadelica
I'm going to preface the following by assuming you are a bit of a novice when it comes to gear, and high end headphones and the associated gear specifically. I will attempt to not sound condescending, as that is certainly not my intent, and if i am underestimating your knowledge, forgive me in advance.
There is a pretty significant difference between the Cascade and ZMF headphones, including the impedance differences.
The Cascade does not scale very much, if at all, meaning you can plug the Cascade into your phone or a $20k amp/DAC combo and it will still sound essentially the same. The ZMFs, on the other hand, scale like mad. If you plug the Atrium into a phone, it will sound worse than the Cascades and you will think we're all doing the same drugs over here, but once you plug the Atrium into the $20k system your jaw will need scraping off of the floor. Now, I am not saying you need to spend mega coin to be able to enjoy ZMFs, but if you chose to, your ears would be rewarded. On the Cascade it would be a waste of money.
Another thing to consider is ZMF headphones are high end audiophile grade headphones, and they will expose weak links in your chain, like using 128 mp3s or Youtube as a music source, or using a PC's soundcard for playback. You can get away with stuff like that on the Cascades, on the Atrium, not so much.
ZMF headphones are worth building a system around, and in my opinion some of the very best sounding headphones in the world, but in order to reach that level of audio nirvana, the downstream chain, the source, the DAC and the amp need to be up to snuff in order to maximize your initial headphone investment.
If that all sounds like more than you want to undertake at this point, feel free to send me a PM and i can offer you some more advice, that way we keep the thread on topic.
Just my .02