TL:DR at the bottom. There's 2 of them.
Okay so I'm on mobile so excuse the formatting. I got this idea from wanting to get my first "real" experience in the audiophile but didn't want to blow my measly minimum wage income on mid tier or high end audiophile gear.
After switching from gaming headset to a standalone mic, I felt I should improve my set up with better headphones. The guide lines for my search were:
Must be open backed as I liked hearing myself without a terrible mic monitoring
comfort beats all, so thicc velour earpads are prefered
REVIEWS
Starting with the Philips SHP9600, I these seemed to have it all for me based on reviews so I decided fuck it, and bought them. Immediately upon use, the earpads weren't terrible but definitely could be better and I purchased Brainwavez Velour Pads. It took some modding getting them on but man These make the shp9600 top tier comfortable.
So the sound? Meh. Just meh out the box. It was okay but it felt dry. Thats the best way to describe it. Now here comes the Fosi K4 mini dac. Bought it for $50, but its now discontinued from what I can tell. Here is the new Q4 DAC for those interested. This dac interested me for 2 reasons: price and eq knobs. This dac is made the SHP9600 ABSOLUTELY GOD TIER. I was incredibly impressed with how much it changed up the sound quality with. It made them wayyyy more detailed and overall super clear. The sound stage is like nothing I expected and blew me out of the water. For just around $150, this set up was amazing.
Now onto the Sennheiser HD559. I previously had the HD560S and never got to listen to them. When I got the 560s, I immediately returned them as I felt they were crushing my head with the clamping force and the little bump on the inside was touching my ear. Just overall uncomfortable to the point it wasn't worth breaking them in. So now because of all that, I was skeptical about the 559 being very similar size and footprint. Luckily it has none of those issues!
Cool they're decently comfortable, but how about sound? Also terrible. Just bad. Very very bad out of the box. I don't if its actually bad or I was spoiled with the shp9600 dac combo. Come to find out about the foam mod you can do to these bad boys and thought "shit, what do I have to loose?". After doing the foam mod these sound phenomenally better. Like much much better. But still something is off.
TL:DR / FINAL COMPARISON
Once the 559 is modded and both are using a dac with eq knobs, these can sound very similar. My overall preference is the shp9600 for the much wider sound stage as the hd559 is just very narrow, but still fine for gaming and such. I feel like modding the backs to make them more open with like a nice metal mesh grill giving them a hd6XX look would make them sound spectacular because even after the foam mod its still pretty closed off and narrow. But over all both are really great for the price. But definitely a preference for the shp9600 for gaming and desktop music listening, the HD 559 is great for mobile listening and walking around as I feel the shp9600 absolutely rely on the dac with EQ to be good audio quality. Think of it as 2 different computer monitors or TV's with the same image on screen. The shp9600 is definitely a wide screen more color heavy and saturated image, while the 559 is a very natural color with a clean 4k image.
2nd TL:DR
Shp9600 relies on the dac and eq to be good, but with it, its a amazing. HD559 is good but requires foam mod. Without foam mod its just bad.
Shp9600 Stock: 6/10
Shp9600 with DAC with EQ and aftermarket ear pads: 10/10
HD559 stock: 4/10
HD559 with Dac and foam mod: 9/10
Thank you for coming to my TED Talk, feel free to ask any questions about either the headphones or dac.
Random edit because I think its funny: just tested an old pair of Skullcandy Hesh 2 I found in my closet and can firmly say they sounded wayyyyy better than the Sennheisers out of the box. Oddly impressed