How much should I spend on a new DAC

Wow… advice all over the place from folks. 
most of it garbage. 
 

lucky for you I also own a project dac box s2+ and a pass amp (not their integrated amp). 
 

first, I got the ifi elite power supply for the project dac. 
 

this made a huge difference. 
 

you have a good dac that with the ifi power supply will compete with dacs in the <$2000 range. I have done this with compare with the qutest and the Pontus and the dac box with the ifi elite power supply and the dac box s2+ is still in my system. 
 

the other area is your speaker cables and other cables. Your cables are well below the capability of your system. 
 

do not replace your integrated amp as someone suggested, you have a very nice integrated amp. 
 

so better cables and and the ifi elite power supply for is what I recommend to take your sound reproduction to the next level. 

Before spending money to relpace your dac, try replacing the coax and power cord with Odin 2 Silver and Gold from Ali-Express. First I replaced a Pangea coax ($169) with an Odin 2 Silver Coax, and was amazed, I then completely replaced all my hi-end cables ($$$$) with Nordost Odin 2 (not Nordost, but incredible value). The gold for component power cords and speaker cables. Power amps need to swing more current. See Amazon for fabulous PCs under $50.00. I bought 2 of these

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Please realize that any high-end brand name cable from Ali express (any cables out of china) is likely fake. 
 

wont comment on their no name cables but I would doubt they are any good for the caliber of audio system you have. 

@jetter - Toslink has less bandwidth, so can eliminate high resolution files as being an option.  The other factor is that using a Toslink required to additional conversions from electrical to light and back.  I’ve not really made an effort to compare, so won’t make any proclamations on SQ as I’m sure there isn’t only one answer. 

celestial_sound,

Dump the PC, even an entry level streamer like a Bluesound Node (130) will best the PC if you bypass the internal DAC with a separate high quality DAC. Others can give you better recommendations on the streamer; but some day I'll own an Aurender. Run ethernet from into the streamer, either with or without something like the Ether ReGen

I agree on the R2R ladder DAC idea, but it has to be better than a Denafrips Ares. I have heard the following R2R ladder DACs in my system and can whole heartedly recommend them:

* Musician Aquarius $3,100

* Musician Pegasus $1,100 (only with a DDC like a Denafrips Iris $550)

* Holo Audio Spring 3 KTE edition $3,100

* Denafrips Pontus II (or the newer Pontus II 12th anniversary $1,850) which soars when the Denafrips Iris DDC is added at $550 - This is what I own

Best of luck to you, this is the fun part