input impedance: preamp = usually 47k
power amp = >20k
inexpensive cd player output = 100 - 200
direct connection (cd + power amp) 200 ohm/ 20k ohm = 1/100
no meaningful signal loss @ low and high frequency regions
so, there is no impedance matching issue.
some people usually say such as "impedance...", showing they are technically oriented... not worth listening to them at all, ha ha ha!