The DAC Scam - Almost everyone believes the hype

I have a Dragonfly black USB DAC. I paid like $120 for it. My question is: Does a $4,000 DAC sound $3,880 better? Or would I be just as well off buying a used Topping E70 Velvet for $275? Would I even notice an appreciable difference between the Topping and Dragonfly?

A salesman at a high end audio store once told me that the reason $10,000 interconnects exist is because people who buy $100,000 systems feel weird about connecting it all together with $20 cables. I know for a fact that $10,000 cables don't sound $9,980 better than $20 cables. But rich people have to spend their money on something. Is there such a thing as night and day differences between decent DAC's, or is it just different flavors and slight variations? Is it milking that last 2% of sound quality for thousands of dollars buying high dollar DAC's?

@facten I'm sorry if my comment came off as a "vieled skeptic question", that's certainly not how I meant it. It's an honest question. Unfortunately, I live in a small city 100 miles away from anywhere that I might be able to listen to high end equipment first hand. I work 5 days a week and don't often have the time to go out of town.

I can't find any reviews comparing the Dragonfly to anything other than other Dragonfly models, red, blue, cobalt. I honestly have no idea how it compares to other DAC's other than by the price I paid for it. Hence the question. I'm not looking to attack anyone or be attacked, just looking for an honest answer to an honest question. Going from a cheap Chinese tube preamp to a Conrad Johnson pv10 was a night and day difference. All I'm asking is if the technology in DAC's is at a point where they are all pretty close and no real night and day differences exists.

@ facten @knownothing Thank you both for your replies. I like the thought of a tube DAC. I don't want fatiguing anything. For clarification, I have a desktop computer feeding a Dragonfly black which is feeding a Conrad Johnson PV-10AL which is feeding an Audiophonics LPA-S500NC into KEF LS50's. 

It sounds like even a $400 DAC is going to be an improvement provided I find one that suits my tastes. I like that ultra tubey sound. Euphonic is the word I hear used to describe the sound I like. Marantz back in the day used to have what was referred to as the "two martini sound". I have always been a fan of vintage Marantz sound. 

It sounds like both of you liked the Chord line of DAC's, and for reasons I can appreciate. I'll read reviews and compare the Mojo's to some of the Topping DAC's like the E70 Velvet and the Denefrips Aries. I read a review that described the Velvet as sounding warm and non fatiguing, but than I read another review that didn't describe it that way.

Anyway, thank you both so much for your thoughtful replies. I may just buy several DAC's from Amazon or other outlets that allow returns and test until I find what suits me. Thanks again.

Matt