What does a separate amplifier do? Confused.

Home audio amps come in three basic varieties. The receiver you have actually combines an amplifier, a pre-amplifier, and a radio tuner, all in one chassis.

Integrated amps jetison the tuner, and have an amplifier and preamplifier, again, in a single chassis.

Finally, there are power amps. These, as the name suggests, do only one thing: amplify sound. A power amp usually has very basic controls; most of the time, just an on/off switch and connectors for your speakers. No volume control, no tone controls, no source selector. Just amplification.

That's where the pre-amp comes in. Sometimes called control amplifiers, pre-amps have a volume control, tone controls and a facility for switching between different sources (tuner, CD player, turntable, etc.) When you connect a separate amp and pre-amp, they are often referred to as "separates."

There are several advantages to using separates vs an integrated amp or a receiver. Each component gets its own chassis and power supply, and can be separately optimized for its individual function. Housing the two components in separate enclosures also reduces the possiblity of interference between the two.

Another major advantage is that separates can be upgraded...separately. So you could, for instance, upgrade your amp or preamp without having to replace all of your electronics at once. That way, you could spend your entire budget at a given time on the best amp or preamp you can afford, and then save your money until you could afford to upgrade the other component appropriately.

Recievers and integrated amps also sometimes allow for partial upgrades. If a receiver or integrated amp has the neccessary inputs and outputs, you can upgrade the amp or preamp sections separately, just as you can with a power-amp/pre-amp combination. But the component in question must have the necessary I/O, as I said.

Which approach is best? At the nosebleed high-end of things, where individual components can easily run into the tens of thousands of dollars, you will almost always find separate power amps and pre-amps. Some mid-level systems may employ an integrated amp or receiver, but again, not as often as separates.

At the low end, where most people (including me) live, you will much more often find receivers, though there are reasonably priced separates for almost any budget. If we are talking about less than $1000 for your amp/preamp combo, there are many receiver choices that will compete gamely against separates.

So, to finally answer your question: it depends. First of all, if you are happy with the sound of your Yamaha, there may be no reason to upgrade your amp at all.

If your receiver doesn't allow you to connect an external amp or pre-amp, you can't add an additional amp at all. If the necessary connectivity is present, on the other hand, you could probably improve your rig, and start on your way toward audio-induced poverty, by upgrading to a better amp or pre.

You could, of course, just upgrade the entire shooting match by buying either

--a better receiver, or

--an amp and preamp that together will out perform your current receiver.

So in sum, you first have to ask yourself if you feel a need to upgrade. Then, you need to determine what upgrade options your receiver gives you, and proceed from there.

Headphone amps are just amplifiers that are optimized for driving phones rather than speakers. They are almost always far less powerful than speaker amps, since phones (again, almost always) need far less power than even the most efficient speakers.

There are a couple of reasons to consider a headphone amp. First of all, some phones, especially higher-end models, require separate amplification in order to sound their best (or in order to sound good at all in some cases.) The headphone output on your iPod or that Yamaha reciever may not do the trick.

Second, the headphone jacks on most portables and home equipment are not very high quality. The headphone jacks on most home equipment are included as a convenience, without much regard to good sound. Most often they are actually low-grade headphone amps, that are completely separate from the main amplifier on the receiver or amp. In other words, most integrated amps and receivers treat speakers much better than they treat headphones. That is by no means a hard and fast rule. Some amps and receivers, particularly vintage models, offer respectable or even good performance.

The bottom line, I think, is deciding how satisfied you are with the sound you currently get from your equipment, and how much you would consider spending to do better. Some people upgrade and are blown away by the results; others hear a tiny difference, or even none at all.

Keep in mind, if you do decide to take the plunge, that an oft-repeated phrase around here is "sorry about your wallet." The urge to upgrade can, in some people, become uncontrollable, leading to a chronic condition called upgradeitis.

Good luck, and have fun .


Edit: Oh, and one more thing. This post is just a very basic introduction. This site offers a wealth of information about just about any audio topic you could imagine, including amps. I urge you to spend some time searching the site.

x2, DrBenway! Great post!

There's a slightly different argument for separates, too. When you really start fiddling with speakers (or headphones, for that matter), you'll often want to match the amp to the speakers.

While a receiver will power most stuff out there, there are some particular semi-exotic speakers that may catch your eye one of these days. If you have separates, you can tailor your rig to your speakers.

For example, you might fall for a pair of Klipsch horn speakers. Those are hugely efficient, so you can power them with something like an 8W 300B tube amp. They sound magical together. Now, suppose you visit a friend's place and he has a pair of Magnepans. You go nuts over their sound and buy a pair. The 300B amp is not going to be happy with the Maggies. You're barely going to get any volume. So you can sell the 300B amp and pick up a monster 400W solid state amp for the Maggies. All the while you can keep the preamp you already have.

The same is true of headphones, but headphones are a much finer point and pickier about amps. You'll have a difficult time finding a headphone amp that will make every headphone sound good, so you often need more than one amp if you have a variety of headphones.

Of course, this is well on your way into the descent into audiophile madness. If you just want one pair (and where's the fun in that? ), you can just have one amp and spend many happy years with it. The HD-650 absolutely needs a powerful desktop amp - the reports you'll see about it being "veiled" mostly stem from a not-so-hot amp. Pair it with a good one and it'll almost sound like an electrostat.

I agree with everything Uncle Erik wrote in his post. Component matching can make a world of difference, for better or for worse. This stuff ain't simple, but for many of this, that's part of the fun.

Portable CD players tend to have mediocre headphone-amp sections, at best. While any quality headphone will sound much better than the lousy phones that come with most portables, it's doubtful that you will get close to the potential of the Senns by plugging them directly into the headphone jack of a portable CD. I can't really be too specific about the HD650s in particular, because I haven't heard them.

One thing you might try is plugging the portable CD into your Yamaha receiver's "Aux" input and then plugging the Senns into the Yamaha's headphone jack (Of course, if you have a full-sized CD player connected to the Yamaha, there's no point to that.) To connect the portable CD, you'll need a stereo-mini to stereo-RCA cable. If your portable CD has a lineout jack, this arrangement should sound even better; plug the mini-to-RCA cable into the CD player's lineout jack rather than its headphone jack. This arrangement will give you some insight into what a quality headphone amp might offer you.

I can almost guarantee that they will sound much better, but "dynamite" is a pretty subjective judgement. Individual listeners vary in their tastes. One phone, at its maximum potential, may appeal to some serious listeners, but not to others. That said, the HD650s are very highly regarded. Search on them here at Head-Fi and you will find a wealth of information and opinions.