You can't better the MB DAC. If you don't like your speakers through the MB headphone jack, you don't like those speakers.
There isn't much or anything a DAC can do about it. Apple DACs are identical the the Becnhmark DAC2 acc to several tests. They are 100% transparent.
You need to change your speakers if you don't like them.
"Apple Dacs are identical to the Becnhmark DAC2", are you serious? Also as per some of your recent posts if the output level or gain are matched then all DACs will be similar sounding!!!
So if I can understand your statement correctly I just need a voltage divider or passive preamp and DAC with high gain output (say 3V or 5V) to get all sort of sound quality offered by various DACs available at this moment in the market. I have to set the output gain to (with the help of the passive) 2.5V to have a taste of
DAC19 or have to set the output to 2V to have a taste of Gungnir or have to set the output to 2.2V to have a taste of Arcam irDAC.
Very very funny.......... So 2 Volts RMS analog output offered by almost all DVD/BDP player will going to sound very very close or even same like Schiit Yggdrasil as it is also have 2 volts RMS output (Single End). All the following terms or parameters are ignore-able like, THD, SNR, IMD, Clock Management, Digital Filter, Analog stage, output impedance etc. etc... ???
One of the most ridiculous claim I ever came across. For your knowledge I already had tried a passive to make my Audio-gd NFB-3 sound like BDP-160, but I failed. As per your claim My Pioneer BDP-160 and Pioneer Elite N-50 will sound same as they both offer 2V RMS output. For your kind information that is also not true.