The transportation company lost my ISK MDH9000. Now i'm looking for a open back with good amount of bass, i have an HD668 and had a HD559.
Fidelio x2 is the best option? What other options do i have?
In the price range of the X2HR? Takstar HF-580 with Aiva pad from Sivga. USD $150ish during sale at AliE before coupons, then $12-$25 for the pads depending on where you buy, with Taobao being the cheapest. The ZX-1 is solid, but dependent on genre due to its peaks and troughs (EDM tends to suffer, for example), and can also suffer with a bright or even flat source.
After that you're better off looking at regular recommendations in that price range rather than Chi-Fi:
Fostex T50RP MK3 - $130-$150
Drop x Sennheiser HD58X - $170 (goes down as low as $130, October-December)
Drop x Sennheiser HD6XX - $220 (goes down as low as $180, October-December)
Drop x HiFiMAN HE-4XX - $160 (goes down as low as $120, October-December)
HiFiMAN HE-400i - $139-$169 currently
The Drop collaborations can go down a further $20 if you're a first time user of the site. Those are all fairly well-described headphones on here, of which I'd mostly look at the HD6XX and the T50RP in general terms, but perhaps the HiFiMAN options for bass response.
There's just not a lot of stand-out options in the Chi-Fi market compared to the above, but there seems to have been plenty of solid development done in the last 12 months (HF-580, Aiva, B20 for planar, Helios for dynamic drivers). It all comes down to what you're trying to get out of the headphone with its bass. If it's strong and fairly clean bass, then the Takstar would be worth a try, but it's with somewhat dark treble and potential issues in the mids (the pads help with this), so you may find the HD6XX a better experience despite the bass roll off.
I've picked through people's thoughts on a lot of open-back and closed-back ChiFi headphone options over recent memory, and it doesn't seem to get much better than the Takstar Pro 82 and the HF-580 in the sub-$250 range. The ZX-1 is an experience worth trying, but if you need a daily driver I'd defer to those Takstar models or work through the list above.
It's rare to see any open back push far past flat bass, let alone the kind of presentation I suspect you're seeking (Harman neutral). As I understand it, beyond bass quantity the X2HR don't really hold up against other options in their price range, and are mostly discontinued anyway.