#1 Take note what impedance your loudspeakers are:
An amplifier’s job is to deliver power to your loudspeakers. Loudspeakers have an impedance rating, which represents how much electrical resistance they present to your amplifier. Impedance is measured in ohms, and the lower the number, the lower the resistance. The less resistance that your loudspeaker presents to your amplifier, the more power your amplifier is going to supply to your loudspeaker. This means that your amplifier is going to work harder, and generate more heat. If an amplifier gets too hot, it will shut itself off. Because of this, the less robust amplifier section of an AV receiver is generally not going to work well with 4 ohm speakers, which present a greater load. Most speakers you encounter will be of the 6-8 ohm variety and will function beautifully with an AV receiver. 4 ohms is a common loudspeaker impedance however, and you will want to take note of the speaker’s resistance before buying if you are going to be using an AV receiver.
#2 Buy an AV receiver powerful enough to do your movies justice:
Since, generally speaking, the amplifier sections of AV receivers are less robust than their more expensive, dedicated amplifier cousins, buy one that has an adequate power rating. Manufacturers of inexpensive, mass market consumer electronics have a tendency to be somewhat optimistic in their published specifications. As a rule of thumb, an AV receiver that is rated at 100 watts per channel with all channels driven will supply adequate power for a dynamic home theater experience. More power never hurts, and if you can get more power within your budget, by all means do so. The more power your receiver has, the less work it will need to do, and you won’t have to worry about introducing loudspeaker-killing distortion. The truth about blowing up loudspeakers is that 9 out of 10 times it is because you didn’t have enough power, in contrast to having too much. The more gain you have to apply on your volume knob to achieve your desired listening level, the more distortion you introduce to your signal. Most loudspeakers can handle quite a bit of loud, clean power. It’s not having enough power and trying to compensate with the volume knob that generally does a loudspeaker in.
#3 Don’t worry about 7.1 unless you live in an old castle:
Unless your listening room is quite long, 20 feet or more, 5.1 channel audio is more than adequate for creating room-filling, three dimensional sound. Besides, DVD, DTV and videogame audio is all 5.1 anyway. There are only a small handful of Blu Ray and HD DVD releases that support 7.1, and they’ll downscale to 5.1 just fine. Almost all AV receivers are going to be 7.1 channel, so you’re set should you ever decide to go that route. Just know that you don’t have to.
#4 HDMI? Do I need it?:
Yes. HDMI is the cable standard that transmits both high definition audio and video in one cable. All your future video components are going to use HDMI, so make sure that your AV receiver has at least three HDMI inputs and at least one HDMI output. If you plan on using Blu Ray, HD DVD or any current or future game console (with the exception of the Nintendo Wii, which doesn’t support it), you are going to need at least three HDMI inputs. Not a problem, because most AV receivers will accommodate you.
#5 Does my AV receiver need to decode the new Dolby and DTS formats?:
Not really. If you have or are interested in Blu Ray or HD DVD, both these formats support new codecs by Dolby and DTS that most current receivers can’t decode. New receivers are hitting the market that support these new compression schemes, but not all Blu Ray and HD DVD players support output of a compressed bitstream. The way that Blu Ray and HD DVD handle audio is different from your DVD player. Your old DVD player outputs 5.1 channel Dolby Digital or DTS over toslink or digital coaxial cable, and your receiver did the decoding. With Blu Ray and HD DVD, the player decodes the audio signal. If you are using HDMI, the player then sends a multi channel LPCM signal to your receiver. The heavy lifting has already been done by the player. If you don’t have HDMI, there is the old toslink or digital coax option, because legacy audio formats are included on both formats. Lastly, for people without HDMI compatible receivers, higher end Blu Ray and HD DVD players have 5.1 channel analog outputs, which many receivers made within the last 5 years will support. In that case, the player decodes the compressed signal, does the digital to analog conversion, and outputs it to your receiver. A compelling reason to get a receiver with onboard DTS-HD decoding would be if your player didn’t support it, which none have until just very, very recently. DTS-HD is barely used in the States, but European readers will be more interested because European Blu Ray and HD DVD releases with DTS-HD audio tracks are becoming commonplace.
While I can’t claim the above points to be the five most important things you need to know before you buy an AV receiver, they are five things that other people may have neglected to tell you, and they are important.
As with any piece of audio equipment, go audition it before purchasing. All electronic components have a unique sonic signature. You may very well find that two units that look good to you on paper sound radically different to you.
My criteria for AV component evaluation is still music. Music is the basis of why we began caring about audio equipment in the first place. If you like the way a component sounds reproducing your favorite music, you will be pleased with it’s home theater performance. Take along some favorite CDs and listen to several components. Listen objectively, and realize that some manufacturers try to grab your attention on the showroom floor with sizzling highs that stand out and make you take notice. It may sound good for a few moments, but you will tire of that sparkle in a hurry. Listen carefully and ask yourself if the unit you are auditioning seamlessly reproduces, without over accentuating, all the sounds, from lowest low to highest high. Generally the units that do so will initially sound somewhat “laid back” to you. Now I said laid back, not muffled. There are components that go too far with their unexciting reproduction of source material. Neither extreme will make you happy, so give it some thought, and buy a component that strikes a pleasing balance between listenability and dynamic sparkle.
