I wanted a new sound system for my 1957 Chevy but did not want to tamper with the original Factory AM radio. Unfortunately our city only has talkback AM stations . One stipulation was the car was not to be tampered with in any way! no holes drilled or knobs or visible systems underneath the dash etc . So to the untrained eye, they wouldn't know it even existed [and it must be able to be removed at a later date if needed] My Husband did all the work for me, as I photographed it [but after his explanations and help, I would be comfortable doing this job myself] We purchased a "Nobsound 10G pro" while in China , These are available on Ebay for $27 including shipping [or $38 with the power pack which you don't need to buy] https://www.ebay.com/itm/Nobsound-NS-10G-PRO-Hi-Fi-DSP-Digital-Amplifiers-Stereo-Bluetooth-4-2-Power-Amp-/273395819252 The company is trustworthy [you will get the product you ordered] This model was chosen over the lesser Nobsound NS-01G because it doesn't require or have a volume knob and has 100w output power. The Amp automatically defaults to "Bluetooth mode" unless a 3.5 jack is plugged into the Aux input and switches the input over to AUX input.[It uses a 3.5mm "Phone Jack" to switch over to Aux] The Amp was so tiny which made us skeptical . So we used a 12v computer power pack and hooked up to our home theatre speakers. We paired my phone to it and tried it out.......................It was crazy, the sound it put out was unbelievable. We tried an MP3 player via the AUX input and the sound was slightly better. It was now we discovered another hurdle, which was listening to FM Radio. To listen to FM Radio from my phone was usually via Headphones ,and the 3.5 headphone wires doubled as an aerial. As soon as I plugged a headphone jack into the phone it switched off the Bluetooth transmitter [this was a phone issue, not the Amp] So we needed to make the Amp AUX input accessible and hidden. We also picked up a male power jack plug and some male bullet connectors which are perfect size for the speaker terminals from a local electronics parts store.