You own a store, you sell 2 brands, which?

I'll go with part to be different, part cause I own there stuff.

KEF and Technics

But Cambridge Audio & JBL would be my close second for the same reason.

Hello,
Samsung and Sony. Due to the lines that Samsung own and Sony because they cover the rest. Did anyone hear about the Sony A9 4.1 surround system. It is supposed to be totally incredible and a totally immersive experience. Maybe we can just add this system to our 2channel rooms so we don’t have to compromise our awesome 2 Channel systems. Have you noticed how many people still have their projection screens in their 2channel rooms. I know I still do. Maybe it’s time to get back into HT or music surround sound. Of course we will still have one seat in the room. 😁
No need to tell people you added the Sony A9 system. 

You can't make money out of a bricks and mortar store that stocks only two brands.

First post answered it.

Yamaha and Macintosh. Yamaha covers every aspect of AV from consumer gear to audiophile. Macintosh will satisfy the snobs.