Is low cost DAC worth it?

I own 4 low cost dac...I use them all

Two Hifime mini one , a-sychronus one ( the better ) the other is a sabre one...

One is used for my computer headphone as a dac , one is used as transport ( a useful added function of Hifime dac ) from USB/optical to toslink for my main computer dac : the french designed battery dac by Christophe Mariac , a TDA 1543 chip, NOS, and very organic sound that work well as a pairing for the mid range of the self powered speakers M-Audio M40 which became now "audiophile sound" modulo my acoustic corner 😁...

For my microzotl 2 and for my AKG k340, my main system, i used the Hidizs Ap 80 pro as i described  above...

All these dac sound different completely, but all are good with the right coupling synergy...

Dac technology became mature few years ago...

+1 @yyzsantabarbara Schitt is a great low cost option, also a great option is the iFi signature DAC and their new streamer. The pair will give you all the FLAC and DSD native (not converted to FLAC) resolutions you need.  I have the pair for a vintage system and it’s fantastic for the money. I also looked at the DAC magic and I’m glad I went with this pair. I’m very pleased. Good luck to you!

iFi and Topping make very good budget DAC's. I have iFi in the shop and Topping in the library. I am not an Apple fan so wouldn't know how they stack up. My hearing is no longer as good as it once was. Even so, the appreciation is still there. I have a used OPPO in the main system. Cambridge Audio could go on your list as well, new and used.

I would buy a low cost one from Amazon (or other easy return site), keep or return it.

IF it improves things, then perhaps do research on the next step up, no rush.

btw, Amazon has ’free returns’, no return shipping costs.

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In my case, real lofi, I was using the PC headphone adapter, rca cable to line in. Advised here to use USB out, to DAC to line in, I bought an inexpensive DAC,

Topping D10s Mini USB DAC, $110.

https://www.amazon.com/gp/product/B08F54TT79/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

it made an obvious difference including increased signal strength/volume.

Years ago I used the optical out on an Airport Express to stream to a Schiit Bifrost Multibit DAC, which I thought was an improvement over the Airport's internal DAC.

I swapped out the Airport for an Allo DigiOne Signature with Shanti linear power supply, total cost less than $500. That was a very good improvement over the Airport and I still use it today.

I recently upgraded the Bifrost Multibit to a Bifrost 2/64, which is definitely better to me than the original, tighter bass, more accurate sound overall.

That means I have the Bifrost Multibit available for sale, offered at $250, please message me if interested. This is the version without the USB card, so please make sure you don't need that or plan to get one from Schiit.

The Bluesound Node seems to be a popular all-in-one solution with updated tech that likely will outperform your Airport and has the DAC included. I've read that adding an external DAC to the Bluesound is more improvement still if you ever want to go there.

If you keep the Airport and use any of the DAC's recommended above, fiber optic cable is the only way to connect to it, which of the DAC input options that include USB, digital coax, and BNC, people seem to find least desirable from a sound quality perspective.