How can I listen HiRes music on a macbook air retina?

Hey, happy new year.

I might be a little late here, but I thought listing the different factors in order of importance would be helpful. (People's opinions might differ on the list, but I'm fairly sure most will agree on the general order.)

(0.) I assume you have high resolution audio files.

1. The actual speakers/headphones/earphones. You will need to listen to your hires audio through something with frequency response/dynamic characteristics, that can actually reproduce the information that's in the huge files.
2. Not bluetooth. There's been a lot of improvement over the iterations, but bluetooth wasn't designed for the kinds of data rates playing back high resolution audio would require. I'd wired connection all the way up to the analog output, but some protocols (mainly using wifi) can handle streaming decoded audio to a receiver at a tradeoff with latency, stability, etc.
3. The DAC (on your audio interface, or sound card) needs to be able to handle the audio format, preferably natively. For example, my display can handle up to 24 bits x 2 per stereo sample, at 48,000 samples per second. If I played a 192kHz file through it, it would ignore 3/4 of the data in its output the way I have it set up now. Any dedicated audio interface would be capable of handling higher resolutions.
4. An amp for driving the audio signal through your headphones can help, and for some headphones with very high impedances, is practically a necessity.
5. If you use software to enhance the sound to your liking, you should be aware that it is, essentially, distorting the sound data before it is played. This isn't a problem per se, and if you like the results, then great, but you might want to make sure that after processing the source, the output is still "high resolution." Having a high res source can help in that there is more data to work with in the software's efforts to make the sound "sound better." But processing that many samples in software, then outputting them again from software is an insignificant task for your CPU.

This is in complete disregard to fidelity of the audio output to the original source, which is completely separate from playing back high resolution audio files.

If bluetooth capability is a deal breaker for you, I'm afraid it's going to be the bottleneck as far as throughput goes. On my MBP, the default streaming codec is AAC with a 256kbps target variable bit rate, and can be coaxed into using 320kbps CBR. This means that anything you play over bluetooth is going to have the resolution of iTunes Plus or Apple Music files.

AAC is a lossy codec, so this means that the fidelity to whatever master it was encoded from is always going to be worse. (Unless you have a lossless file, in which case it would be comparable).

There are few ways to get around this. High-rate bulk data transfer is just not what bluetooth was intended for. If you have ever used bluetooth handsfree headsets or your car's handsfree connection for calls, you know what SBC sounds like, which is what the bluetooth audio stack falls back on if your device doesn't support AAC.

I get the sense that you are partial to Sony products, their solution for playing high-resolution audio wirelessly is LDAC. It's a codec with more efficient encoding and compression schemes that allows for up to 96kHz/24bit audio to be transferred over bluetooth. It's also a lossy codec (by necessity) which means that the 96/24 audio you receive is an approximation of the 96/24 source.

Unfortunately, this is moot in the current situation of Apple not supporting LDAC /Sony not licensing LDAC for software implementation — except for Android.

The most likely reason for this is LDAC's competitor, aptX. It's the same basic concept: more compression, better algorithms for encoding audio to send more of it over bluetooth. aptX is on most recent android devices, but not on iOS. It is on macOS, though, and if your headphones/speakers support the codec, and the configuration process goes without a hitch, it should be used automatically.

So you have a Mac, which has aptX and BT, but no LDAC, Sony headsets with LDAC and BT, but no aptX, and a Sony walkman, which, if you have a bluetooth capable model, supports LDAC and BT, but NOT when it is being used as a DAC. (Sony doesn't license LDAC for/sell DACs which can transmit its output through bluetooth, since it would effectively be a <more popular codec> to LDAC converter.)

At the moment, it looks like you'll have to load up your walkman with any dsd files if you want to listen to them in a higher resolution format than what most music streaming services provide.

I'm using Boom 2 to enhance the sounds on my 2017 MacBook Air. Works on my Bluetooth headphones as well. Although the difference is far better noticeable on the external USB sound card which is hooked up on my hifi set.

You can find Boom 2 in the App Store.

At my place that would be a yes I think. My hifi has a jack output for headphones. My sound card is the same.

https://www.terratec.de/details.php?artnr=10715#.XCdN3y1x-hc This is the one I have. They never made Mac drivers for it, but it just works right out of the box.