Disclaimer: My favorite artist is Mark Knopfler.
The 1770 doesn't come close to the T1's. This is my final conclusion. Are they good? Most certainly, I do not regret my purchase at all. But they can't really compare to the T1's. It's most likely because they're closed.
They're no where near as detailed as the T1. Soundstage was actually surprisingly good, but still no where near the T1. Upper bass is a bit boomy. Bass extension beats the T1 though. In general, the bass is 'fuller' than the T1, but not as controlled. The 1770's is more of a 'shake-your-head' kind of bass, where the T1 has a strong focus on controlling the bass, and producing the right sound, though it lacks the 'shake-your-head/body'.
Mids timbre of the mids is about the same actually. The 1770's keeps up well here. The mids are fuller (notice a trend?) on the 1770 compared to the T1. Listening to a bit of metal (something I've not done for some time, as the T1's aren't a good fit) on the 1770's left a smile on my face. Plugged in the T1's and listened to the same songs. The 1770's wins, no contest. The sound is thin on the T1, but the 1770 handles it with elegance and POWER. My ears are lusting for my 1770's. They want more power, more metal!
The T1's have more sparckle than the 1770. I suspect this is due to the (in)famous (and with Elise, tamed) treblepeak. The 1770's aren't far behind though. It's a good thing though. I'll be using these headphones out of my phone, possibly with a solid state amp in the future, so not having to tame the treble (with tube magic) is a blessing.
From a pure audiophile point-of-view: Which is better? T1, no doubt.
From a pure enjoyment point-of-view: Which is better? Debatable. Depends on what music you listen to.
My test was done using the Feliks Audio Elise amp with a pair of Fivre brown-base 6N7G as drivers and a pair of Mullard 6080 as powers.
Edit: This is the T1 Gen1.
Edit2: This is with the velour pads. Haven't tried the leather pads.
