@Flanaaandeeers you don't want flat, you want them to sound a certain way. The drivers are an inch from your ears so there are nearfield effects that have to be ironed out. You have to try them out. One thing I miss about my local hifi shop that went out of business was that they had all the cans with a switchboard. I haven't heard one that I like more than the ATH M50, but other engineers (with money) like Sennheiser and Grado. I don't know anyone who uses Sony, but I see them in the field. Most of the Sonys I have tried have an artificial high end, but once you get used to your headphones, you adjust. The Sony's are revealing of noise in the recording, so if you need to monitor for noise, factor that in.

AT make also the M30, I haven't tried them but they routinely show up on eBay for $25 if you want a cheap pair of cans with relative balanced sound.

I've been a Sennheiser man, but have also had AKG over the years. I had Sony WAAAAY back in the day but like @DrDave said I thought the high end was overhyped and a bit fatiguing.

For really cheap headphones i've been hearing good things about the JVC HARX000 Line. Each model had gotten good reviews. The HARX300 $15 HARX500 $21, HARX700 $37 and HARX900 $60. These aren't the ultimate in audio quality, but from what i've heard they are VERY good and close to the ATH M line. At those low prices it's worth a shot.

unfortunately the PU or PVC they use on ear pads deteriorates over time, oils on our skin and ozone may contribute to deterioration, but I usually find third party replacements on eBay or Amazon

https://www.amazon.com/s?k=MDR-7506+ear+pads&ref=nb_sb_noss_2

unfortunately the PU or PVC they use on ear pads deteriorates over time, oils on our skin and ozone may contribute to deterioration, but I usually find third party replacements on eBay or Amazon

I need to do that for my Sennheiser 7506!

Already replaced my gel pads on my Remote Audio 7506 last year.