Even quality companies will put inferior opamps for the headphone output. You can find many quality headphone amps for a few hundred dollars. Schiit is a good place to start.
headphone question
I'm going to buy a new pair of headphones for occasional listening, such as the AKG K142HD or K272HD model. Will I need a headphone amp for these phones or will my McIntosh C712 pre-amp be sufficient since it has a headphone jack? Any other suggestions would be helpful.