BEST CAR HEAD UNIT. NEED EXPERT ADVICE?

I work at Best buy. I know a lot about car-fi. I know that every head unit we keep on display uses MOSFET amplifiers to keep it cool, cheap, and small. These mosfets put out on average 14 watts/channel and at most 20 watts/channel. Everyone knows to get better quality/louder volumes you need to utilize the preouts on the back of the headunit. By then quality will be dictated by the amp you use, and a sufficient power source. Cool.
So this guy tells me I know nothing because I say a sony will sound the same as a kenwood and pioneer and jvc etc. Because they are all chinese mosfet amps. And because youre putting it in a '98 ford f150 with road noise and engine noise and $40 reinforced paper pioneer speakers. I told him the only differences are the sales they happen to be on, bluetooth capabilities, sirius, hd radio, usb, analog, and the ease of EQ settings. I firmly believe that radios are all capable of the same quality sound out of the box. And he told my manager to fire me.

So, my questions are for the car audio masters, I want to know

WHO makes these mosfet amps. Is it all brand X amps in brand Y head units? Or is it actually sony amp in sony head unit?

WHAT are the differences between brands? Are there notable digital samplers going on behind the scenes that nobody knows about?

IS there ever an argument to take seriously when someone wants sq from the speaker outputs at 15-20 watts? IMO you are going to distort by the time it is loud enough to drown out road noise.

ANY other info you can tell me that I can't read on bestbuy.com? I understand that one head unit can do bluetooth and one can't… Its how i've been selling the past year… I always will find out a customers needs and recommend the cheapest solution based on that. If the parent wants their kid to have hands free calling, I give them the kenwood, pioneer sony jvc or alpine that is the best price at the time. My conscious is clear when it comes to selling at best buy. I'm here to learn and not to argue about overpriced services or geek squad protection, so keep those opinions off this please.

I wouldn't argue with any of what you said about the sound quality potential of any head unit.
I guess the lesson here is to feel the customer out first. If they're a know-it-all but don't know |)ic|< you might need to "ease" into the facts about a the output limitations of a stand-alone 17w head unit.

It doesn't really matter if the HU is assembled by hand in tibet by an albino monk. 15 or 20w rms ain't gonna blow any doors off no matter how much somebody wants it to or believes it can.

High end dacs and parametric eq's are great toys, but they're not going to matter much at all w/o external amps.

Mosfet is an acronym for a type of transistor. They're not special or exclusive. They're basically the standard for audio output and power supply transistors.