Not really, there are no separate headphone amplifier circuits in those integrated amps. They have simple resistor banks in between the speaker terminal output that feeds the headphone input. You actually are quite likely to get a degree of sound degradation that way (for instance the reported warmth for the NAD 3130 which I have also owned). That isn't to say that the sound will be bad, not at all, but in all likelihood, aside from power output, a well designed, dedicated headphone amplifier will provide the best performance with headphones. Of course there are multiple factors at play, but if all else is equal, and a dedicated headamp has enough power for the load, and is well designed, it will perform better than an integrated amplifiers headphone section which 99% of the time will just be resistors.
This is coming from somebody who uses a 180W NAD M3 as my headphone amp, but I don't have any yucky resistors in the way, I had a dedicated speaker tap cable made so that my headphones are powered directly from the speaker output of the amp. And to put that whole myth of the "extra" power advantage to rest. That is hogwash. If you have unused power it will provide absolutely zero value to you, there is no bonus for unused watt, that is just a completely unfounded myth.
As long as your amp has the headroom to swing and provide the burst power requests that the load requires, not a single extra electron of power will flow. So if you think having extra unused watts beyond what you need for dynamic power bursts (headroom) is doing anything for the sound, think again. Unused power is simply unused power, and I have had 180W behind my headphones for probably 8 years now so if anybody should be buying into that myth it would be me. Enough power is enough power.