And do pay attention to output impedance as well.
If the headphones have a differing impedance per frequency (many dynamic hps will have a bump in the upper bass region for example), driving them on a high output impedance amplifier will cause a higher relative SPL in that frequency range (voltage divider).
But even on headphones with a flat impedance curve that will matter as per output power. If say the headphone and the amp have the same impedance, half the voltage drop will occur within the amp, therefor severely limiting output power.
I have measured a few different headphone outputs of different devices:
(does not discriminate against clipping, actual useable power might be lower on some of those devices).
You can see that decent mainboards tend to have around 80R Zout, Amir found the same on a Gigabyte.
And with that you can see that the have just about the same output power into a 32R5 and a 218R6 load - while lower impedance headphones tend to require more power for the same SPL.
A voltage limit doesn't hurt the output signal of the amp just limits the max SPL more than you might like, a current limit means clipping and therefor coarse or distorted etc. sound.
I can tell you from experience that the AKG K702 for example sounds horrible driven from my mainboard, while the 250R Beyer T90 does just fine for normal listening levels.
The L30 will tick all the boxes and work just fine with every normal headphone, be it very sensitive IEMs (low gain option, super low noise floor) or your 600R DT 990 (6Vrms with 2Vrms input at 3x gain).
Edit:
The Denon 5200 for example would require four times the source voltage with a 80R output impedance amp as compared to 0.1R.
The sound wouldn't change much, +1dB in the lower bass area.