Basics: Anyone?!

BASIC TERMS: INTEGRATED, PRE AND POWER AMPS, RECEIVER
Let’s get basic: A power amplifier simply provides the juice to your speakers. No volume knob, just a single input and a single output right to your speakers. A pre-amplifier, on the other hand, provides no wattage but contains the volume knob and multiple inputs for your iPod, CD player and so forth. An integrated amp is both a pre and power amp combined and is all you need (along with your speakers and an iPod) to get going. A receiver is an integrated amp with a good ol’ radio thrown in for kicks (today, receivers are a rarity in stereo but form the bulk of home theater components).

TRUTH IN NUMBERS: FREQUENCY RESPONSE
When you see a number like 50Hz-20kHz, it’s referring to a loudspeaker’s frequency response. Human hearing is technically rated as 20Hz to 20kHz, but our upper hearing limit is, typically, around 18kHz, and we can feel bass down to 1Hz. Speakers usually have tweeters rated above 20Hz, but this upper limit is sonically undetectable. An average bookshelf speaker will have bass down to 50Hz, while a floorstander may be rated in the hgh 20’s or 30’s. Only a subwoofer is able to dig all the way down to 20Hz and below.

The truth is, however, that measurements mean jack. A manufacturer may say their speaker goes down to 20Hz, but when you listen, the bass is thin and lifeless. Likewise, another manufacturer may rate their speaker upwards of 60Hz, but the bass is a lot more full and powerful. The reason this happens is due, in part, to different methods for measuring frequency response as well as appealing to certain audiophiles who crave numbers.

That said, super low bass is fun but isn’t a prerequisite to amazing hi-fi. The vast majority of music happens above 100Hz. Great 100Hz to 150kHz performance is what separates the men from the boys.

SPEAKER SENSITIVITY AND POWER HANDLING
Numbers like “85dB 1w/1m” refer to how much wattage is needed to make a speaker dance. A speaker with, say, a super low rating of 82db will need hundreds of watts while a speaker with a sensitivity 95 or above needs as little as 5 watts to shake the walls. Sensitivity has no bearing on overall speaker quality, just the required juice.

Power handling is another spec you will often see that is almost meaningless in real world situations. A speaker with a 50 watt power handling rating can easily be run with 1000 watt amps. Likewise, a speaker with a 200 watt limit can sing with only 50 watts. Simply match the wattage to the sensitivity and you’re good to go.

BIG OR LITTLE SPEAKERS?
One of the secrets of hi-fi is that bigger isn’t always better. A 2-way speaker (tweeter and woofer) will always be easier to setup and tweak than a massive speaker with 3+ drivers. It’s easy to get seduced by the goliaths of audio, but the truth is those monster speakers are made for monster rooms and aren’t ideal for typical spaces.
While the big speakers sound fantastic, do yourself a favor and buy a 2-way speaker and add a sub. You’ll thank me later.

CD PLAYER VS TRANSPORT/DAC
Occasionally, you’ll see people talking about transports and DACs instead of CD players. What gives? A CD player takes the little digits on your shiny silver discs and turns them into the analog signal required by your preamp or integrated amp. A transport will look like a CD player, but instead of sending an analog signal, it sends a digital signal requiring a separate Digital to Analog Converter (DAC). General hi-fi convention holds that a transport and DAC will sound better than a CD player, and most separate DACs these days offer USB input for direct computer connection.

TRUTH ABOUT BIG WATTS
Spend ten minutes in Best Buy and you’d be convinced that wattage is the only thing that matters. In hi-fi, however, the number of watts is a meaningless measure of quality. Think about it like this: turbocharged Honda hatchback with 500hp may have far more power than a Porsche with 300hp, but is the Honda a better car? No way. Same with the marketing hype surrounding big watt systems. In fact, some of the best amps in the world have under 50 watts and can drive speakers to ear-bleeding levels.

TRUTH ABOUT CABLES
When starting out, cables should be the last piece to spend money on. Each cable, no matter what the manufacturer says, has a specific sound. For under a $100, you can find a cable with the right sound for your system (or better yet, just ask the speaker manufacturer which cheap cables they like). That said, if you start out with a company’s least expensive wire and move up to a more expensive model, you will hear a difference. Whether it’s worth the big jump in price is up to you, but starting out, don’t get caught up in the cable hype.

TUBES, SOLID STATE, CLASS-D
There are probably more flavors of amps than there are of speakers. Push-pull tubes, SETs, pentodes, solid state, digital and more. While different people will have different tastes, all amp types will sound fantastic. Simply match the right amps to your speakers and you’re good to go. If you're confused about an amp choice, consult your dealer or the speaker manufacturer.

TRUTH ABOUT SUBWOOFERS
Some audiophiles thumb their noses at subwoofers. Well, these audiophiles are fools. Subwoofers are fantastic and many sub manufacturers make killer boxes with bass that sounds nothing like the flubbing car audio stuff. In fact, subwoofers with digital EQ and room correction are quickly becoming the only method for obtaining accurate, super low bass.

DO TWEAKS WORK?
In some audiophile hangouts you’ll see weird devices and tweaks that supposedly make your system sound lightyears better. Don’t believe the hype. The devices that do indeed improve the sound do it on the scale of 1%. Nice speakers and amps are where the magic is at.

Source:SonicFlare -- Sports Cars For Your Living Room

Ah, loads of facts there.

And plenty of scope for never ending arguments too

Very useful information! Must read for anyone venturing into audio.

However, some interesting (controversial?) stuff:

Transport+DAC vs. CD Player: Any opinions?
Subwoofers: I agree!

More comments please!

- Prasad

Music is best heard WITHOUT a subwoofer.

A movie sounds great WITH a great subwoofer.

Oh well, I heard someone very popular giving some phase funda against the usage of a sub in stereo. I do not accept that but I still like to keep a 2 channel system, well, only 2 channels.

Another one.

To feel the bass down to 1 Hz, well, one has to be either in a well or in an open field. I wouldn't think it is possible to produce 1 Hz sound in a normal living room.

Although i agree with having full range towers would be ideal for music.
Don't you a think a quality sub woofer well calibrated with decent bookshelf speakers can give you near identical performance?

Specifically, if you consider price/performance ratio, you will have to go really high up to get the bass performance of a sub-woofer.

However, the major impact seems that since bass amplification responsibilities are taken up by the sub, the main amp is able to give cleaner mid-range and trebles. This is something that I have personally experienced.

Personally I dont care about the ".1" being there or not when I listen to music. If I feel that the addition of a sub can improve the over all quality of the music played and if my perceived image is putting a smile on my face, then why not?!

Controversy in this topic: Subwoofer

I'm not going to the usual blah blah of pipe organs etc, but don't you guys think these days many of the music tracks contain instruments / frequency goes below 40hz, that even a decent floorstander can't handle?

Certainly a subwoofer is necessary to produce the full frequency range of instruments in particular and sound in general. There is a good frequency map here:
Interactive Frequency Chart
...with the Piano (of course) plunging the lowest.
And instruments go well above 20Khz as well:
There's Life Above 20 Kilohertz! A Survey of Musical Instrument Spectra to 102.4 KHz

The challenge however is the integration of the sub with the speakers and the room. It can be done well (but which requires significant investment) and the overall sound is greatly enhanced. But the problem is with budget subs which sound pretty terrible and out of sync with floorstanders.

On the point of perception of above 20khz bandwidth as with SACD, interesting article here on the effect on the listener:
The Truth About Hi-Resolution Recording?