As a Beyer fan who owns the DT770Pro 80 and 250, DT880 Premium 600, DT990Pro 250 and Premium 250, as well as a T1, I'd say no, you don't need the DT990. IMHO it's the worst headphone in that bunch, the only one not worth buying AT ALL, FOR ANY REASON, and in my opinion not listenable without heavy equalization because the highs in stock form are just incredibly sharp, bright and totally unrealistic, and the mid bass hump makes it muddy with any music that involves bass. And I say that again as a Beyer fan, obviously not minding bright headphones, unless they go too far. DT990's go too far. I know my DT990 is 250 ohms, but I did listen to the DT990 and felt it didn't sound any better. It's an incredibly bright headphone that has an upper bass boost and a lower bass roll off, which makes it sound very uneven, because at the same time you don't get that deep bass rumble of the DT770 (or DT880 relative to mid bass), but you get the sort of muddiness in the lower mids and upper bass that you usually expect from a hump in that area of the frequency. The mids feel thin and cold, and uneven at the top, and on top of all that are those incredibly tizzy, metallic, sharp and unrealistic highs. So it's a headphone that sounds super bright at the top, thin in the middle, and slow / muddy in the bottom. The only advantage it has over the DT880 is a slightly more open sound and a slightly bigger sound stage, that's it, in any other area the DT880 walks all over it. DT990 is not fun. If anyone thinks DT990 is fun, let me know where you live so I can avoid that place, I don't want to meet you.
And no, it's not the gear, my system is more than good enough for 990's if it does justice to the T1's.
