Welcome to SHENZHEN AUDIO TECHNOLOGY CO LTD
Our categories are:

1. Bluetooth Music Receiver

2. USB 3.1 Type C adapter

3. Smart Bluetooth bulb

Digital OR Analog... Not Both
I purchased this to use with an integrated AV system because it had both analog and digital outputs. Unfortunately, I didn't realize that you had to choose one or the other, not both simultaneously so I'll still have to add a digital to analog adapter for this system to function as intended. Unfortunate that this wasn't clear before purchasing…

Excellent (but pay attention to the D/A switch.
I bought this a couple weeks ago and it will fit the bill perfectly. MAKE CERTAIN TO SWITCH THE DIGITAL/ANALOG SWITCH ON THE BOTTOM OF THE UNIT (I of course did not read the instructions). I use it in the garage and outside at the pool. When the neighbors come, all they have to do is Bluetooth connect; it turns on the AMP automatically and they have music without having to get into my house.

sounds great, blue light is annoying, a bit high $
First, and most importantly, it sounds great. Based on just sound quality I'd give it 5 stars. The blue light is ridiculously bright and flashes non-stop when not paired. My on/off switch doesn't seem to work but that wouldn't bother me if the LED wasn't so bright. In my opinion, it is a bit expensive. You can order in China for $20 but then the shipping brings you back up. I think a 'fair' price would be closer to $30, but that is just my opinion. You can get a 7 channel home theater receiver with blue tooth at Best Buy for $150 so $40 for just Blue Tooth seems a bit high.
Except the $150 7 channel home theater receiver with blue tooth at Best Buy will be a cheaply made product.

Great Product
Very Happy with this product as it is what I expected.

Great sound and easy to use
Connected through TOSLINK and paired to iPhone immediately. Sound through Yamaha Receiver and Energy Connoisseur speakers is excellent. It is quite expensive, but quality and performance is better than expected.

Excellent product
Very happy with this bluetooth receiver. Sounds excellent and setup couldn't be simpler. Only complaint I have is that the blue LED is way too bright and unnecessary in the first place. Otherwise this is perfect for my needs.

Bluetooth Excellence
I bought 4 different Bluetooth Receivers that are now just sitting around. I'll find use for them but not on my main system. My speakers are the Magnerpan 3.7 and if you're familiar with them you'll know the kind of equipment you need to drive them properly. I hooked up the Parts Express Bluetooth to my Processor through tos-link to let my processor's DAC take over. I was stunned by the quality of sound I heard. The other ones, and some more expensive did not sound anywhere as good. If you hook those up to mediocre systems you would probably say they sound good. For he money and of course a good DAC these are your best bet. I love it.

Great Little Box
This little gem is exactly what I was looking for. It works perfectly and is small enough to fit anywhere in my sound system. I haven't tested the Bluetooth range but it works great in my application. Just be aware of the audio switch on the bottom. You can select digital out or RCA out. Mine came with digital selected & I was using RCA so it fooled me for a moment.

Q: Will this device work with a vintage Marantz stereo receiver?
A: Yes as long as the receiver has standard line level RCA inputs.

Q: How many sources can this unit pair to at the same time?  I have a bluetooth receiver now that seems to get "married" to the first source that you hook it to and then there is always connection problems when you want to switch to another source.
A: No, Bluetooth is always a one to one relationship unless you buy a device that is specifically designed to do more. We do sell some models that are transmitters which can split the signal to two receivers, but the receivers we carry at the moment can only receive one signal at a time.

Q: Can this be hard wired into my 12v truck for acc power or will I need a regulator?
A: This requires 5VDC, 1,000 mA for power so a regulator will be needed.

Q: Will this device automatically turn on when it receives power? (eg when it connected to a usb charger in a car, when the car powers on)
A: The unit has a on/off button so it will need to remain in the on position for it to turn on automatically when you turn the car on.

Q: Can this be powered from the USB port on a Yamaha Receiver?  It is 5v 1A.
A: Yes that should be sufficient power for this module.

Q: What is the power output? HOw can one purchase an Amplifier without knowing the Power output and Signal to Noise ratio?
A: This isn't an amplifier, it's just a bluetooth receiver that is a source to your system.

Q: Is there a similar product available as just a board for integration into a custom chassis?
A: Yes.