What DAC upgrade made you say “DAMN, that sounds SO MUCH better than my last DAC”?

@chorus, well I'll mention Audio Note.  I was happily using a Border Patrol DAC in an otherwise AN system, and was happy with the sound.  Switched to an AN 2.1x Sig. and the difference was amazing.  It will only do CD quality sample rates, but the improvement in layering, decay and dynamics are very obvious.  Couldn't be happier!
@Pengun, switch to the Denafrips Pontus or Venus, and use the Pi2AES I2S output for a real upgrade in sound.  It certainly makes a difference going into my PS Audio DSJr as it has the I2S connection.  

The PS Audio Direcstream DAC. I cant even remember what I was using before it. It even gets better every time they have released software upgrades, which , by the way, are free. I highly recommend this DAC.

I have been listening to a recent purchase of an Esoteric K-03XD for not quite two weeks and am (coming to grips?) with its sound. It doesn’t sound like a SACD/CD player in the sense that I’m familiar with and it doesn’t sound like a turntable. As a "died in the wool" analog person that listened to digital music as an afterthought (used to listen to digital as an afterthought), has in the last few years realized just how good digital sound can be and I’m now at a crossroads. Just one example of the kind of music making this player produces is a rip of a Patricia Barber recording of "Blackbird" that I can only describe as the wettest cover I have ever heard. When I mentioned this to the seller the other day , he laughed and told me a wetter sounding recording of new music by Barber is on its way. A pile of CD’s that I was going to dump for what I thought were bad sonics, I now have a renewed interest in. I will be buying more used discs at local second hand shops. More fifty cent discs and less $135.00 plus vinyl. I’m getting older and getting up every seven minutes to change an lp is not what I’m interested in doing much of anymore. In a way, like purchasing a Degritter, it makes my life better by making it easier to enjoy my music and simplifying the process of doing it. 

I have a few DACs in my house and I've auditioned others. I first cut my teeth on an Audio Alchemy, now Elac DAC.  Peter Madnick did a great job with this entry level DAC, then sold it off to Elac.

I then did a lot of research and wanted to hear what R2R was all about.  I bought a Holo Spring KTE edition and was very impressed.  It was a nice improvement in soundstage, and smoothness.

Around the same time I auditioned a Chord DAVE.  I liked what I heard but the difference between it and the Holo Spring were not worth another $7500.  About a year later I began working from home and wanted a DAC in my office.  Knowing what the Chord sounded like I bought a Hugo TT2 and have been able to directly connect a pair of Omega CAM monitors and run the Hugo in amp mode.  A great nearfield sound.

Then the Holo May was released.  All reviews were glowing.  Already liking the Holo R2R sound I took a chance on the May.  This was the most significant DAC upgrade I have experienced.  The soundstage, image depth and tonality are deep and true.  Something you need to hear.

People have been responding to this post with improvements other than the DAC.  I have made improvements all along the chain, from the server hardware and software, power supplies, circuits, wiring, cabling, shielding, room treatments, really everything.  The biggest impact component will always be the speakers.  Preamp and DAC are probably the next impactful.  

An Auralic Vega G2 clearly bettered my PS Audio Direct Stream.
My current Mola Mola Tambaqui clearly bettered the Auralic.