Ahh, I have many things to say about this!

First, a trip in the Wayback Machine to 1997 or thereabouts, where I had a crappy Dell PC on my desk and had just splurged on a pair of Grado Labs bottom-of-the-line headphones. When I plugged them into the CD-ROM's audio jack, what came out sounded like great music. When I plugged them into the sound card, it was a mess. I could hear the graphics card working. Scroll a window, listen to screechy noise.

Fast forward to more modern times and I've observed similar issues with modern computers. With most Macs I've tried, the audio is pretty solid, but often has a noticeable noise floor. Dead silent music and you still get some hiss.

I've tried a number of different external USB DACs, including a CEntrance DACport, a generic Chinese USB-DAC amplifier, a TEAC A-H01, and a handful of line-level devices like a Griffin iMic.

All of these devices are about getting out of the electrical nightmare of the interior of your PC. After that, it's all about your needs.

For example, the CEntrance DACport (mine is older than the current one shown) has a crazy, headphone-level class-A amplifier. But, the built-in volume knob was super scratchy when you turned it. Seriously? Yeah. The generic Chinese USB-DAC amp ran great, until a month past its first birthday it just up and failed. The Teac has been running like a charm for years, and I'm using it to power my gigantic VMPS RM2 speakers without issue, albeit in a relatively small room. I also use it as a headphone amp. I've used the line-level devices like the Griffin iMic back when I was doing DJing, so you'd have one channel for the room and one for you to preview what's next.

Suffice to say that I'm very satisfied with the Teac USB DAC that I'm using. My only complaint was that it requires the installation of a driver to make it work. If my Teac blew up today, I'd buy another one tomorrow, so I guess that I'm endorsing the Teac models that you're listing.

Also, I'd avoid Bluetooth. That's just another source of compression artifacts.