Best DAC under 2k US ?

I've been most impressed by my Channel Islands VDA-2. For sure opt for the VAC-1 power supply. That leaves you with plenty of cash left over so that you can buy some decent cables as well. And it's Made in the USA as well. My second recommendation would be a used Adcom GDA-700. There's one on eBay right now.

The Calyx is interesting. Gotta try one soon.
For me the asynch USB performance connected to a Mac Mini is important

I heard the Calyx and would say it meets your ask dead on. Natural sounding but still musical and sweet. Detailed without being etched.

Neko Audio D100 is PERFECT for your requirements.

www.nekoaudio.com

You will need to either 1) make some basic choices (see below), or 2) trust your ears.

Choices - How are you going to connect to the DAC: USB, S/PDIF or optical? Do you prefer upsampling/oversampling, or NOS/native rate? Do want to drive headphones directly from your DAC? Do you want a volume/gain control on your DAC? Remote?

For me, right now, I'm a big fan of the Antelope Audio Zodiac DACs. Three models with diferent price points, but they all sound great. But, frankly, there are no bad DACs; at least I have never heard one. Just some that I prefer more than others.

Well you are being given recommendations under 1K and I would agree that those are solid recommendations. I personally prefer the W4S over both the Havana and Minimax Plus which I also own with the cavaet "in my system and for my tastes". The Havana offers what you are looking for in that it is warm without any harshness whatsoever, no sins of commission for sure but ultimately sins of ommission in my experience. The Plus has the detail but in my system it sounds somewhat lean across the board, less preferable to me than either the Wyred or Havana, YMMV. The W4S offers warmth, detail with substantially more weight in the tone of instruments than either of the other two with no harshness, it also is a bit pricier. Not to belabor the point but we all have different systems and different priorities.

You might want to try a Havana used and hear first hand what all the fuss is about, NOS tube based. It is every thing you request at a great price point. If you find that you want more, particularly detail and frequency extension, you might want to try the W4S or some of the other pricier ones that probably offer that. Not knowing your system and not having auditioned all of them my comments above are based on extensive listening to each in two separate but very different systems with the conclusions being the same for both myself and the owner of the other system. I also own an Oppo 95 which IMO for all that it offers is the best value in low cost digital that I have come across. I am currently using it as a transport but can see sometime in the future having the modwright tube mod performed. There are many great choices out there for budget buyers but one thing to keep in mind is that some of the fringe/esoteric manufacturers' products might be better purchasing used than new. Otherwise you might take a bigger hit if you decide to move on to something else.

Blue Circle 509

I would also highly recommend the MHDT paradisea or Havana DAC. I have had both and still use the paradisea in one of my systems. It's a great DAC especially for the price

The Mhdt Labs DAC's such as the Paradisea and Havana are also good choices and worth looking into. Lots of reviews on each of those. I had an original version of the Paradisea that was quite nice sounding. Choice of 5670 tube can tailor the sound to your personal preference.

The Metrum Octave DAC mentioned above has received very favorable user comments. It appears to be a very good value.

There is a Metrum Octave on here new for just under $1000. It is a NOS dac that has gotten exceptional reviews.I am currently waiting on one from the factory myself. I had a Rega NOS dac and really liked it; the Metrum is suppose to be better, although the Rega has more outputs and inputs for those who need them.

You should probably consider the Eastern Electric Minimax. Maybe even the previous version used.

A non oversampling DAC such as the 47 Labs Shigaraki could be a consideration as it fulfills your criteria. Pre-owned ones show up on Audiogon from time to time at favorable pricing. New retail pricing may make them less competitive with some other lower cost offerings. I'm very happy with mine that I've been using for the past few years.