So I've been really enjoying my Fostex TH900 (which I got for an insanely low price of $1080 CAD from Canada Computers brand new, was really lucky to stumble upon it, it was the last or second last pair on clearance). Thanks for the recommendation by everyone, I really am grateful, it's perfect for both Metal and DnB subgenres I'm into. I owe you guys for that.
Now, do you guys feel that an open back pair of headphones would complement the TH900 really well or is it a bit overkill given my subgenres below? I'm new to full headphones - I've only used IEMs for the last 12 years like most kids, the only open backs I've owned were the Sennheiser HD598, 6xx (hated both, but that's because of the typical Sennheiser sound signature, not necessarily it being open back) and tried one of the entry level Hifiman planars from my friend (HE-400 I think, I only remember they're not well liked here and frequently went for 60% sales).
I was dead set on trying out the Rosson RAD-0 but I'm not sure how I'm going to feel about switching between two headphones given my genres listed below, it seems a bit tedious. I'm very open to trying them/buying a pair (pun semi-intended), price isn't a major issue but if I'm not going to end up using one pair of cans at all then I might as well save the $1-2k right? Also as an aside I don't think I'm quite ready to spend 3-5k on TOTL open backs like the FAD D8kP just yet. I doubt I would be able to appreciate the marginal differences at my current "level" if you will. Is there certain subgenres of Metal where the RAD-0 would shine above the TH900?
I guess my only option is to audition the RAD-0? Rosson has a good return policy. I've called all local dealers listed on Canuck Audio Mart in my region (Calgary, AB) but no one carries it. Any input is appreciated but I'm in no rush - I look forward to my TH900s everyday right now because of limited time being spent outside and all my work being done from home. It might be my favorite purchase of all time so far (if I'm exaggerating it's only slightly) - only downsides are the cable since it's the original and an unappealing aesthetic to me personally (I quite like the Sapphire Blue mk2 that I've seen in person at M&S, a local dealer, but they wouldn't price match $2500 CAD to CC's $1080 CAD for the original TH900).
It sounds like, to me, you are looking to "upgrade" more out of desire to just try something new and less out of necessity. And, believe me....that's where I've mostly been for the past few years with this hobby lol. The upgraditis is severe.
For what you listen to and from your description of what you like and haven't liked in the headphone game, it sounds like the TH900 could potentially be endgame for you. With that being said, trying something different that complements what you have is the beauty of this, as long as it doesn't cause financial harm lol.
I think an open-back planar is the logical step for you to try a slightly different experience to complement what you already like. For you, my vote would be trying the Rosson RAD-0, for sure.
You will find, in particular, the bass quality to be quite different with the RAD-0 than the TH900.