A good desktop DAC and high-end headphone setup is meant to be the last desk audio gear you buy, lasting a decade or more if you pick solid gear. When you buy once, you skip the endless upgrade cycle of swapping out cheaper amps and DACs every year.
Shop the mid-summer audio gear clearance events when manufacturers drop prices to clear out inventory for fall releases. Last year's model is usually identical in sound quality to the brand-new gear, but you get it for a lot less cash.
Remember that the 0% intro APR for 15 months on purchases and balance transfers is a hard deadline, not free money. If you still have a balance left when those 15 months are up, the standard interest rate kicks in on whatever you owe.