I have both and without an EQ I'd easily prefer the D2000s. The bass is the only thing on the L1s that is more punchy (has more speed/attack) and refined compared to the D2000s. On the other side the D2000 sounds airier, with a bigger sound stage and better instrument separation, has more natural sounding mids (voices) and more resolving highs. But none of both headphones is free from coloration. For example violins on the D2000 sound some kind of metallic (like on some Ultrasones) while veiled on the L1. My HD800 has along with the T1 nice sounding violins, T1 makes them a bit silky and HD800 a tad aggressive. HD800 is here slightly more realistic over the T1. L1 and D2000 are a good amount away from that.
For classical music, which is -if you know it- easier to judge, because you can have real life comparisons with that without any technology in between, I've made a list on German Hifi-Forum.de, concentrating on music of Richard Wagner:
Here it is in German school grade system (from 1 = very good (A) to 6 = very bad (F))
"copy&paste plus some more":
ACHTUNG!: It's only where I place the different headphones with the music of Richard Wagner. My "subjective opinion"!
Source:
Denon DVD-3910
Amp:
Meier Audio Corda Cantate.2
Bereich "sehr gut":
Sennheiser HD800 : 1,2 (mit Mod eventuell 1,1, vielleicht auch 1,3 - bleibt also 1,2)
Bereich "gut":
Beyerdynamic T1 : 1,7
Bereich "befriedigend":
Ultrasone HFI-580 2,8
AKG K701 : 2,9
Sennheiser HD590: 2,9
Sennheiser HD650 : 3,0
Denon D2000 : 3,1 (wäre die Höhendarstellung anders, dann trotz Bass 2,4)
Beyerdynamic DT48S: 3,2 (wäre mehr Bass vorhanden, dann 2,3)
Beyerdynamic DT880 (2003): 3,2
Beyerdynamic DT880/600 : 3,3
Sennheiser HD600 : 3,4
Bereich "ausreichend":
Philips Fidelio L1: 3,6 (mit simpler Höhen-und-Bass-EQ-Anhebung und 2000Hz Korrektur 3,2)
Beyerdynamic DT990 Pro: 3,7
Beyerdynamic T70 : 3,8 (ohne "Dosigkeit" 3,1)
Beyerdynamic T50p: 3,9 (ohne "Dosigkeit" 3,7)
Beyerdynamic DT231 : 3,9
Sennheiser HD595/120 Ohm 3,9
Sennheiser HD598 : 3,9
Sennheiser HD565 : 4,0
Audio-Technica AD900: 4,1
Sennheiser HD545: 4,1
Ultrasone HFI-780 : 4,2 (ohne "Metall-Klang" 2,7)
JVC HA-RX900: 4,5
Bereich "mangelhaft":
Sennheiser HD 540: 4,9
JVC HA-RX700: 5,0
Audio-Technica AD700 : 5,0
Beyerdynamic DT990 Pro: 5,2
Sennheiser HD595/50 Ohm : 5,4
Bereich "ungenügend":
Grado/Alessandro MS1i (Bowls): 6,0 (mit Pads 6,2...
)
The source:
http://www.hifi-forum.de/viewthread-211-414.html