[Serge44]

Еще немного о нагрузке на усилитель при одновременном подключении двух пар акустики:

Most consumer-grade gear is designed to SAFELY run with an 8-ohm speaker load at FULL POWER draw. The problem with connecting multiple sets of speakers (in parallel, keep reading) is that it lowers the load "seen" by the amp. Two 8-ohm speakers in parallel is the same as a 4-ohm speaker. Now, pretty much any amp can handle driving a 4-ohm speaker at low volumes, but many of them will have trouble at higher volumes. The problem is that half the impedance (4 ohms vs. 8) draws twice the current. Pulling double the current through the output devices (the big transistors on the large heatsink) makes more heat. Heat is the killer of all things electronic. If the amp has output devices rated for the high current that will be developed by using 4-ohm speakers, OR if the amp has current-limiting circuitry to protect said output devices, AND if the heatsinks are able to dissipate the increased heat, you are fine. If not, the output devices fry... literally.

Some cheaper designs hook up the second set of speakers IN SERIES with the first, rather than in parallel. This configuration presents a nice easy 16-ohm load to the amp, but at 1/4 the power output so you won't get much volume out of either set when they're both turned on.

Pretty much all pro gear is designed to handle low-impedance loads and have power ratings at 4, 2, and sometimes even 1 ohm, with many amps able to handle a dead short on the outputs, which would instantly kill a consumer amp.

Take off the cover of the receiver and monitor the temperature of the heatsinks, that'll tell you how your amp is doing. You should be able to put your hand on the metal and keep it there for a few seconds without pain... any higher and you're in the danger zone. The Marantz 22xx line isn't rated at 4 ohms, but I've run my 4-ohm Magnepans with my 2250 and it handled the load no problem although I didn't really crank it.

http://www.audiokarma.org/forums/sho...92&postcount=9