When I did own the D7000's, I too enjoyed them very much with a vintage SS receiver. A 1979 Hitachi HA-330. Noise floor was higher than I'd like, but the synergy was unprecedented.
Since the re-cabled D7000 is my only premium offering inside the listening room, I couldn't help but ignore naysayers and output impedance. So, to better evaluate my OTL amp, I brought in a few higher impedance cans for nearly a month each. My D7000 at a lowly 25 ohms more than held its own. AND still remained my preference with the amp. I listened to a re-cabled HD600; AKG 701; Beyer DT-990 600 ohm.
And I especially like the D7000 with my 1980 Pioneer SX-D7000...dessert anyone?