Getting good sound from MacBook via DAC.

Why bother a MacBook way too much noise with all the digital switching. 
No comparison to a good player with built in HD I compared and ended up with the best player ,as well as best buy and award winning.
CHECK OUT the Aurender 100-H player. It has a very hood Linear power supply,
A 120 Gigabyte Solid State drive just as a memory buffer,No other does at under $2500 as well as a 2 Terabyte Hard drive plus allows for a external  HD hookup.
ALSO THE Proprietary Conductor App for all your library organization 
With Tital with MQA . Please do compare  and excellent build quality weighs over 
10 pounds. And have won a bunch of awards .please do compare .

The BDA-2 is a fairly high end DAC, right?  So why would the OP want to buy a new player that has its OWN DAC, like the Aurender?  Do you think that an Aurender + BDA-2 would be appreciably better than a properly configured mac -> BDA-2? I'd be a little surprised, but am not judging, just saying.  The DAC in the aurender is pretty good though, right?  So maybe that would be a better solution - just sell the BDA-2 and use the $ to buy Aurender?

FWIW Tunes -> audirvana works pretty well for a lot of folks for about $80 for the software.  Worked pretty well for me at least. 

Personally, I'd humbly suggest that it would might be worth playing around with the mac first before investing in another box.   I'd second the suggestions about bitperfect, and audirvana (again, worked well for me into a bifrost and later into a Schiit Yggdrasil).  Might also try different power supplies etc.  Also he/she didn't say anything about file formats, so we're not sure if they're compressed low-res files, or sweet lossless ones.  Given the BDA-2, would suspect they're in a reasonable format though.

If the OP is going to invest some $  - just throwing it out there - maybe a Bryston player (BDP-1, BDP-2, or Pi) playing from a NAS or maybe from an external HD might be another step up the audio chain - maybe?  The pi at least is not crazy expensive.  After using a an old Mac -> audirvana -> Schiit for a while, I wound up making that step but I've got to say that, for me, a bigger bang for buck was installing audirvana - i.e audirvana -> gungir was probably at least as good as awful iTunes -> Yggy.

One question I'd like to bring up is: NAS vs attached HD?  In the AS review of the BDP-2 they said that direct connection sounded better than NAS, which would seem to contradict some of the advice above.  No personal experience with that, just sayin' what they said.  Could see it working both ways, the total isolation of NAS from player with electrons flying through space vs a close and friendly external HD sharing noisy power supplies? Would be a good experiment ....

Do an experiment. Take a MAC Mini, Mac Book or PC, download Pure Music, Amarra, Audirvana Plus, Bit Perfect. Pick your track, load them all up with the track at the same place, and A/B switch play the track. Use the same DAC.

You will hear the differences. Why? Isn't digital digital? And that difference is without considering all the colouration the PC/MAC is adding along the way with noisey power supplies, audio filters etc.

This has driven me to develop a 'no compromise' media server. It's nearly there. Ground up best practice design and build - software - hardware. Bit-perfect codec, lossless digital signal processing, ultra high spec DAC and power supplies.

It will satisfy me, because I'll know exactly what I've got from source to destination. Whether it becomes a product for others remains to be seen.

From that test I did three years ago, I concluded my MAC Mini setup would always be sub-optimal.

I spent a year trying to tweek out the best sound from my audio dedicated Mac mini but always felt there was a layer of "hash" separating me from the music.  Bought an Aurender N100H with a Nordost USB cable and aaaaahhhhhh...  Nirvana!  Rest of my system is Classe Sigma SSP, Amp5, ProAc Response 5, MIT cables, LP12/Benz.  In retrospect, I feel like I just wasted a year.  It is that much better.

Guys, he has the MacBook already, and he hasn't yet explored the free and low cost options. If he configures the Mac properly and tries adding a $100-150 USB-SPIDF converter, and he still doesn't  get the sound he likes, then by all means replacing the Mac with an Aurender or similar dedicated streamer makes sense. But until then, it seems irresponsible to recommend replacing existing hardware for thousands of $$$ when there are free and low cost options that can make a world of difference. In particular, the USB-SPIDF converters can do wonders for cleaning up noisy USB signal. I don't doubt that some of you can here the difference using a purpose built streamer, but that doesn't mean it should be the recommended solution of first resort in a situation where OP already has hardware.

My two cents, of course ...