A tape-out and a pre-out are not the same thing.
They are taken from two distinctly different parts in the signal chain.
A "Tape Out" is taken from after the source selector and before the volume control. No other processing is done, aside from a phono preamp. I'm not sure that they do digital signals but I could be wrong.
A "Pre Out" comes after all the preamp/processing stages and before the power amp.
Let's start from the back:
A "pre-out" takes the signal after it's gone through the entire preamp stage. That means source selection has been done, the volume control has done it's thing, any tone controls have been applied, additional gain
may have. been applied, and any other stuff the preamp does, well, has been done.
Now, let's talk about that source selection and "may have" stuff.
Generally, aside from a phono preamp, no gain takes place before the volume control, which comes after the source selection.
And, a true "tape out" routes the signal between the source selector and before the volume control. Aside from a phono preamp, the tape out sends out the full signal that's available from the source. I can't really say about it's internal tuner or processor, but many external sources such as CD's are capable of putting out 1-2 volts or thereabouts.
In any case, many power amps should not have a problem with it, as long as they have enough gain and internal means of controlling the volume, which many don't, which is the rub here. Both speakers will be operating at the same level on the volume control,. Remember, it's not a "zone" type situation with either of the choices he's offered us.
As for an external "integrated" amp, it's going in through a high-level input and through it's internal preamp anyway so many concerns about signal level disappear.
Iffin's it were me, I'd use a tape out and feed it to an integrated amp/receiver simply to have independent control over those additional speakers. One may need more juice there as opposed to the main speakers.
Of course, most units have provisions for two sets of speakers anyway and that could be a poor man's way out of the entire situation.
Let's hope this gets the monkey off my back.
And good luck tracking me down. I'm posting from The Bahamas.
