Heya Brad!
If you have a very strong preference for studio monitors, you should also have a very strong reason. Studio monitors don't make sense as a categorical preference. If you're using studio monitors it is because of necessity, not preference. I'll explain that in a bit. ***
If you do need them, however, use the HS7's. The HS7 is the modern-day version of the Yamaha NS-10, which was made about 30 years ago. The NS-10 is the most common monitor used in recording studios, especially recording studios that have been around for a while. The best recording studios in the world are the ones that have been around the longest. The NS-10's you can find on eBay, but they are not a powered monitor.
The HS series monitor has two output options. XLR or 1/4". Both connections have the same sonic signature. XLR has a more reliable connection point because the grounding pin in the 1/4" jack can sometimes bend. You should pick whichever connection works easiest.
Since you are connecting your monitors to a computer, you should connect your monitors to a DAC or a midi interface. You can also connect them directly to your computer using a XLR to 1/8" "Y" cable. Using a dedicated sound card with studio monitors is the worst option out of the ones you have. It will add coloration to the sound of your monitors, interference, (remember, the inside of a computer tower is flooded with electrical signals and interference coming from the power supply and every other component on the motherboard) and impedance. A discrete DAC (digital-to-analog converter) that sits on your desk outside of your computer a better option since you are using active monitors.
*** Explanation.
The best recording studios in the world are using monitors that are decades old because they sound terrible. The purpose behind studio monitors is to balance the volume (or mix) of sounds in a way that the song will sound the same across an array of platforms (headphones, car stereo, home audio) and to make any errors in that balance (or mix) as glaringly obvious as possible. An analogy: studio monitors are the equivalent of a woman with no makeup on.
A beautiful pair of active monitors that have the option to add an active sub (since you mentioned you like 2.1) is the AudioEngine A5+. They are $400 for the pair and I believe the sub is $350. About the same price as a pair of the HS8's.
This is just a caveat, but you can think of the difference of sound engineers and audiophiles as the chef and the person eating the meal. I'm still learning a lot on the audiophile side of things, but I've been a musician since I was about 8 years old. Worked as a sound engineer in 2003-7 and recently auditioned as an artist and got the green light to work with Electrokitty Recording Studios in Seattle, WA (electrokitty.com). They have worked with Dave Matthews, Carrie Underwood, Everclear, U-2, Nas, Kendrick Lamar, and a lot of very talented artists that aren't pop stars.
I'm really enjoying learning and listening to the beautiful world audiophiles get to experience. I hope this helped you a bit because I don't often get to reciprocate on this forum because I am still doing most of the learning on this side of things.