There are so many head gears and so many different ways to put them together. On top of that everyone's tast is different. I am simply sharing my experience. Hope my experience can help some because I received great help while researching my gears. Not here to offend anybody.
Just started serious listening with headphone two months ago. Before that my system was Marantz CD63->Audio Alchemy DDE1.0->EICO HF60 mono blocks(total rebuilt with separate power blocks)->MartinLogan Sequel. Had this system for about 17 years. Boy that's a long time without any upgrade now think about it. It is not a simple task to get every component ready and start listening. I want a easier way to listen to my music. So about two month ago I started researching and acquiring headphone gears.
I decided to recycle the transport and DAC. Here is my current headphone system Marantz CD63->Audio Alchemy DDE1.0->La Fegaro 336C(not Dark Voice) with Sylvania 6SN7GT and GE 6080 tubes->Philips X1(Mediabridge cable) and Sennheiser HD580(with HD600 cable)
I mainly listen to Classical, Opera and pop Jazz, sometimes a little old fashion pop. From all the reviews I read, about 20 of them, just about everyone agrees that HD580/600 is great for Classical/vocal, and X1 is great for Jazz. Many said the X1 has a recessed mid/vocal. With the stock 6N5P everybody's unanimous opinion seems to be true. To my biggest surprise after I replace the stock 6N5P with a GE 6080, the mid range and vocal of X1 become so liquid and smooth without loosing it's authoritative/tight/punchy bass and clear/airy/sparkly high. The X1 mid/vocal also gain quite some body and moved forward, now it's a perfect balance among high, mid and low. The X1 suddenly became "alive" if you know what I mean. (BTW, the stock 6N8P was way too noisy I had to replace it with a Sylvanic 6SN7 NOS right in the beginning of my listening. All comparsion was based on 6SN7.) With the stock 6N5P power tube HD580 sounded so sweet in the mid/vocal, but for some reason the HD580 become too forward and the sound stage is a bit mixed up. Well, I just found a setting that fits all my music genre which I never thought can be done with my limited budget.
Before I settled with HD580 and X1 I also tried Beyerdynamic DT880-32ohm. It was simply way too bright for my taste. Also, I couldn't hear any bass. Maybe the DT880-600ohm is beter, at least that's what I read on review, but Amazon kept sending me the 32ohm one instead of the 600ohm one I ordered. Tried twice in getting the 600ohm failed both times. But Amazon still deserve a hug thank-you from me, without their mistakes I most likely won't try the X1.
It is so sad that not too many people pay attention to the Philips X1. With proper source and amp it is truly a gem with budget price. Buy the Fidelio X1 without second thought. You will smile every day, just like me.