impedance matching buffer

I'm looking for a simple passive pre-amp with an impedance matching buffer and volume control and a couple of inputs.  Is there anything like this out there besides the First Watt B1? (really hard to find and I'm not a DIYer) Is an impedance matching buffer something that is common in a preamp?  Please excuse my noob ignorance
Perhaps try a transformer volume control. It’s passive and because it’s a transformer, it will maintain low output impedance. Antique Sound Labs make a nice one, T2 DT.