What makes a DAC so expensive?


You can buy a Cambridge Audio AXA25 25 Watt 2-Channel Integrated Stereo Amplifier | 3.5mm Input, USB Input for $225, and most DACs seem more costly. 

I'm wondering what it is that makes a Bifrost 2 almost as expensive as an Aegir and 3x's as expensive as the Cambridge product, above. I would have thought an Aegir would out-expense a Bifrost by a factor of two or three. What are the parts that make the difference? 

I'm wondering if the isolated DAC concept is one that comes with a "luxury" tax affixed. Can anyone explain what I'm getting in a Bifrost 2, or other similar product that justifies the expense...?

Thank you.
listening99
What makes a DAC so expensive:

Audiophiles who think that the more expensive a product is, the better it must be....
The complexity of the build ,the power supplies, are essential in the S/N  and purity of signal, many aftermarket linear power supplies are over $1500 alone ,brand name , how fancy the case 
If a R2R multi ladder dac each resistor has be matched to possibly hundreds of resistors ,clock ovens all kinds of add o to empty your wallet DCS dacs with all maxed out power supplies ,and super clocks $90k combo, the best sounding digital on the planet 
that can rival the best of Anything out there, but Slightly out of my budget !!
Those that don’t want to spend the money justify having not done so.

Those that have spent the money justify having done so. 
And so the wheel turns, and turns, and turns. To me it comes down to what camp your ears tell you your in. 
I went from a Bluesound Node 2i to a separate Audio Mirror DAC followed by replacing the Node completely with the addition of a LUMIN Streamer. Both phases of the transition were substantial but heavily weighted towards adding the separate DAC. No comparison.
@mvrooman1256

curious if you went from node 2i to lumin while you had your audio mirror dac already... if so:

- any perceivable sq improvement in going bs --> lumin?
- what connection used?
- what speakers and amps in system?

presuming you used node 2i bnc digital out... not its poor onboard dac

many thanks
@jjss49  I started out with Schitt Vidar monoblocks and a Schitt Freya+ preamps with a Node 2I functioning as my DAC and streamer.  Speakers are Magnepan 1.7i’s.  I added the Audio Mirror DAC and continued to use the Node 2i with an coax cable as a streamer only.  The difference was substantial and obvious.  Way less harsh, bigger sound stage and things just seemed to open up.  A lot more space to the music.  I then added the LUMIN streamer and completely removed the Node from the chain.  A difference but not as big as switching to an outboard DAC.