Q: I have some 1970s-vintage small Advent speakers. They are in great shape and are rated at 15 watts. I'm in need of a new receiver to go with them because the old one died. How do the "old" power ratings compare to the "new," inflated power ratings? I'm seeing ratings of 100 watts per channel. I don't want to blow out the speakers.
A: It is hard to compare "old" vs. "new" power ratings across the board because different brands rate different components in different ways.
Separate power amplifiers tend to be rated accurately, so you can compare power ratings and it is apples to apples. When you compare a 5.1-channel surround sound receiver to a seven-channel amplifier, the receiver might say, "50 watts per channel with two channels driven," which means that when you drive all five channels simultaneously, the power output is significantly less. The separate amplifier will say, "75 watts per channel with all channels driven," which makes it a true 75 watts, all the time under all conditions.
The bottom line for you is that you can use almost any amplifier or receiver with your speakers. The 15-watt rating does not have much real-world significance because there are very few amplifiers rated at 15 watts or less, and, more important, you are more likely to destroy speakers with an amplifier with too little power, not too much.
For example, say you are playing music and the average power need is 4 watts. Suddenly, a crescendo kicks in and 40 watts are required. If you have a 15-watt amplifier, it will run out of power at 15 watts and start creating distortion, which will burn out speakers very quickly. If you had a 50-watt amplifier, the amplifier can reproduce the 40 watts cleanly and you will be fine nearly all of the time.
But, "nearly" doesn't mean "always." There are limits to this. You could not hook up a 1000-watt amplifier and use your tiny speakers to fill a concert hall with sound. Even with clean power, you would blow them out.
Nonetheless, for most listeners and speakers in home situations, there is a saying in the audio world that "you can't have too much power."
The Onkyo TX-8020 I have recommended in the past is rated at 50 watts per channel and sells for $179. It is rated at 20 Hz-20 kHz with 0.08 percent THD (distortion) with both channels driven, which is a conservative, real-world, "old" kind of a power rating, not an inflated rating. It would be a good match for your speakers, which are quite good despite their age.
Send questions to Don Lindich at firstname.lastname@example.org. Get recommendations and read past columns at www.soundadviceblog.com.