Pairing different amps , pre-amps , cd players ???

They say if you pair different make amps/pre-amps/cd players in your system, some will sound better or worse depending on which brand the component is paired with. Wondering if anyone on Audiogon has come across this and did you find it can effect sound quality in a big way. If so are there any rules I can follow or things to be aware when trying to
upgrade - are there particular components where this doesn't matter much (i.e. preamp to amp/ preamp to cd)? Thanks for your help and looking forward to reading your responses... Peter
As a starting point, from preamp to amp (and I would assume source to pre-amp), you want to have the upstream component's output impedance to be at least 10x less than the downstream component's input impedance. Across the entire frequency band. As specs across the entire frequency band for input and output impedance are not always given, it is generally a good idea to go with 20x greater or more to be safe.

Another thing you will want to pay attention to is your gain structure. You don't want to have so much gain that you are playing at the bottom end of your volume control, where a small turn of the dial produces a large bump in volume. There are other sound quality reasons as well that you don't want too much gain as well, but I will keep it short and not go into those here.

Then you get into a more subjective pursuit of tweaking the balance of speed, warmth, timbre, etc. For some folks getting the right balance involves having one of these components being tubed and the other solid state (tube amps seem to generally impart a greater tube sound than preamps, for better for worse). Others find the balance they prefer (and which works best with their speakers) from an all tube or all solid state system.

Hope this helps. I am sure others will chime in before too long.
Hi Peter. Attention to the pairing of any components always matters. You just can't get around it. Once you research the specifications of amps, preamps, output and input impedance etc. there are no guarantees for success. The sound may be satisfying or may not be. It's more than just specs. My advice is to try and hear other audio systems, whether at dealers or other homes, and when you find a sound you like, try to replicate the components in that system. Or, buy components from the same line of a particular manufacturer (if you like the sound) of that manufacturer. That is a at least a guarantee for synergy.

When putting together a system, speakers come first, then find an amp that matches your speakers. Match your preamp to the amp, then sources to preamp. I learned this over time by reading in forums like this one.