Looking at getting first air brush compressor...

I personally have a Badger TC910 which I found for sale at a great discount at Michaels. It is quiet and does the job. Another possibility is this "point zero" which seems to have gotten fair reviews and is quiet also and much cheaper. I would check other reviews.

https://www.amazon.com/PointZero-Twin-Piston-Airbrush-Compressor/dp/B004KNHGCI/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=soundproofempire-20&linkId=71c35210bdd252138ddd73e8e2ebb03f&language=en_US

You do want a storage taank on your machine or it will run continously. I have 2 airbrushes, one for acrylics and one for enamels (just my preference) but I have a quick disconnect adapter to switch from one to another. I see no need to be able to run two simultaineously. I also put a closed cell rubber matt on the floor under the compressor to help dampen noise.

My opnion is save some money and with the money saved buy an ultrasonic bath to help clean your brushes.

I run a Fortress w/ 2 gallon tank.  Is fairly quiet at 60db, and will run up to 135 psi, so it can be used for other chores as well.  Has 2 outlets.  Around $160 or so at harbor freight.  I caught a coupon and gave about $135 for it.  Not as compact as a dedicated A/B unit, big not overly large either.  Weight is around 30 lbs.

No issues with it over 2 years.

IMHO, the two airbrush option is not all that important.

The storage tank will help dampen out the pulsing airflow, but to be honest, I never had a problem using just a compressor without a tank.

Sound level is a consideration if you paint near family members or neighbors.  I used to run my Badger diaphragm compressor out in the patio in the evenings, but had to stop at 10:00 to avoid annoying the neighbors.  The noise did carry late at night.

Use a quick disconnect fitting so you can easily detach the A/B and hose from the compressor if you store them separately like I do.  It will also facilitate A/B swapping if you do that kind of stuff on the fly.

HTH

Air Compressor for airbrush are just to expensive.

California Air Tools - The Largest Manufacture of Ultra Quiet, Oil-Free & Lightweight Air Compressors - CAT-8010

I got me this.

Consider CO2.  Dry and zero noise.  I switched 25 years ago and never regretted it.  I do have a cheap compressor for backup though, ran out of CO2 right when the pandemic hit. 

As others have said, there's no need to spend the extra money on a high-end airbrush manufacturer's compressor.  I've had this one for a little over 5 years, airbrushing almost everything (I even got to the point where I mask and airbrush individual dials on instrument panels), and it has been very reliable:

 https://www.amazon.com/gp/product/B006ACB6D2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I'm considering getting an air tank and filling/refilling it with nitrogen as an alternative.  I have pretty easy access to compressed nitrogen for a nominal fee, and it might be nice to go completely noise-free.  Just like CO2, its also a completely dry gas.

Also, I know you already have the Iwata HP-CS in mind, but for a good first airbrush, I would also recommend having a look at the Paasche H model.  I have used the same Paasche H for about 35 years and only recently tried an Iwata HP-CS.  Frankly, I found the whole flushing/cleaning process on the HP-CS to be a PITA, and haven't found any situation yet where my Paasche H couldn't do the same job.  Cleaning is really easy, as it is external mix, so every part that paint touches easily comes off the airbrush with a single tool.  I drop all of those parts into a jar of MEK and run them in an ultrasonic cleaner between each color for a complete cleaning.  An air cap, needle, and color cup set are fairly cheap (around 10 bucks), so I have 3 sets, which allows me to keep painting the next color while the previous color's parts sit in the cleaner.  I like to call it the AK-47 of airbrushes...can't break it...can't jam it...it just keeps right on shooting.

Hello! I use a compressor taken out of an old fridge for airbrushing. I got it over 25 years  now... - got it fo about 0$ plus some parts I added later. It's as quiet as a fridge and does a fine job. Over the years I have customized it a bit with a pressure regulator and a nice carrying handle.

People here on the forums usually ignore messages like that - makes me wonder a little bit, why do you want to throw away perfectly good compressors (in old friges) and then pay good money for machines that are too loud and not well suited for the job?

Oh well - good luck spraying and have a nice day

Paweł