Eric, thanks for the incredibly quick response! You've thought of things that hadn't occurred to me, and I'm grateful for the additional wisdom.

tca, some dB versus power calculations might help. If five watts is background, say 70 dB, 20 watts (you meant 20, not 2, right?) is four times as much, or six dB more, so it's only 76 dB! 60 watts is three times that amount of power, or about 4 dB more, or 80 dB! The reality is that background (70 dB) is, say, one watt, sorta loud at 80 dB is about 10 watts, and louder than comfortable, 90 dB, is a hundred watts.


The amount of power going to each speaker does depend on whether you use a switcher or not. As Eric points out, the switcher puts a resistor in series with the whole bunch of speakers to ensure that the amp never sees too low of an impedance. But as Eric also points out, even if that resistor gobbles up half of the power going to the speakers, that'll only be 3 dB, which sounds like going down one step on the master volume. For practical purposes of ballparking what you're doing, then, you can just divide the amp power by the number of speakers. It's harder to get that most of the time a listening level you can talk over is in the neighborhood of a watt of power!

oex, it hadn't occurred to me that the second zone amps aren't really built to power a half dozen sets of speakers, but after reading about this over the last couple of months, I'm never going to hook up more than two pair to any second zone amp again. (The used Sonamp 260 is a great idea.) I've just been involved in searching out an amp for this purpose, and most such amps are around $700. That pricing alone backs up the idea that second zone amps shouldn't be used for multi-room setups: if the guys who build amps made for this kind of thing have to charge $700 for an amp that will do it well, how can a small part of a $500 to $1000 A/V receiver possibly be built to perform the same?

Fred, you're right about current controlling the loudspeaker. Here's where that protection resistance in the switcher is a bad thing: it limits the current that can get directly to the speaker, lessening control over movement of the cone. For more controversy and disagreement about what this means, if anything, search this site for "damping factor." Impedance matching VCs don't do this; they transform the impedance rather than adding a resistor to an impedance. So when you use that $1000 pair of speakers, the switch box impairs current to the speakers, affecting fidelity, and volume controls insert reactances and can't linearly handle high power, affecting fidelity. Those $1000 speakers deserve their own amp. This is exactly where you'd use twelve channels of amplification with preamp level volume control instead of one bigass power amp divided up into six rooms with switch boxes and/or VCs between the amp and the speakers. The performance of those expensive speakers suffers if they aren't powered in the (usually) more expensive manner of having their own power amps.