I'd like to add a device to a home stereo that would allow me to cast to it hifi audio from a phone or laptop. Don't need video. I know there are bluetooth receivers for this but I'm less sure of audio quality. Any firsthand recommendations?

I see highly-rated devices like this one on Amazon are over $100. Is that the reality of it?
https://www.amazon.com/Audioengine-B1-Premium-Bluetooth-Receiver/dp/B00MHTGZR4

Are there other technologies (AirPlay, etc.), perhaps wifi based, I should look into?

 

I have used this one in a Dewault jobsite radio and also in my garage stereo. The sound quality is good.
It uses usb power adapter.
https://www.amazon.com/dp/B00S92C4YG?ref=ppx_yo2ov_dt_b_fed_asin_title

 

I've had success with every cheap Bluetooth to AUX adapter I've purchased on Amazon.

Buy by the stars.

Edit: just re-read your post. I think I might have it backwards.

Edit 2: on second thought, I think I got it right.

 

I've put one of these on my wish list:
https://www.amazon.com/dp/B0D45K89KX

There were many similar devices with similar specs and ratings, but only this one offers digital audio out over optical.

 

I've put one of these on my wish list:
https://www.amazon.com/dp/B0D45K89KX

There were many similar devices with similar specs and ratings, but only this one offers digital audio out over optical.

For $20, how could you go wrong?

I might buy one myself just for fun.

 

but I'm less sure of audio quality.

The BT receiver should state which protocols it supports. They usually max out at MP3 circa year 2000 quality. Perfectly fine for casual listening. Probably falls far short for most audiophiles.

 

Probably falls far short for most audiophiles.

Everything falls short for most audiophiles.

 

Everything falls short for most audiophiles.

In this case they might have a good case. First whatever is being streamed is stored in a lossy compressed format. That gets de-compressed and re-compressed again in a lossy format to fit the BT streaming protocol. Then that gets de-compressed and fed into a questionable D/A chip. Or maybe no chip if it's a digital output. But it still gets re-compressed at least twice. I have a BT receiver that works well but lacks any high end frequencies.