On Wed, 26 Apr 2017 12:59:29 -0400, wrote:

On Tue, 25 Apr 2017 12:40:23 -0400, Fred McKenzie wrote:

Reference http://www.coutant.org/matching/a95.pdf

This link PDF file is quite useful. But it dont specifically state what
devices can be plugged into them. I know there are unbalanced
microphones that have a 1/4" plug on their cord, and things like a
guitar. But it does not specify if the preamp output from a receiver
will match....

One question I have, is there some standardized output (in ohms) for
things like the preamp output from a receiver, or the output from
something like a DVD or Tape player, or even a small MP3 player?
I assume all these devices have some sort of "standard" output
impedence, or are they all different?

Most of the time I just hook the stuff up, and if it sounds OK, then I
just use it. But I know this commercial equipment, with balanced inputs,
is in a class of it's own.......

There is little need to match impedances unless you need to maximize
power transfer (for example, coax for radio equipment). Almost
everything you run into with consumer audio equipment has hi-z inputs.
The outputs are designed to drive those hi-z inputs (which is very
easy to do as long as the outputs are lower impedance than what they
are driving). The term for this type of signal is line level (as
opposed to mics and guitars which can be much lower level). As you
have discovered, professional audio equipment uses 600 ohm balanced
lines in order to minimize hum and be able to handle longer runs of
cable. Any preamp with RCA connectors for its output can drive the
hi-z unbalanced input of your amp. If you want to use the 600 ohm
balanced input, you need a preamp with that type of output of a
converter, but the hi-z inputs (ie, RCA connectors) will work just as
well in normal home use.