Pre-Amplifiers.

Rotel RC-870 Preamplifier "Stereo Control Amplifier"

Now, how to control the Amplifier output... Pre-Amplification.

This area is full of options from line source switchers with or without a phono-preamplifier to straight source CD player to Amplifier.

Magnavox CDB-473 Remote Control with volume adjustment buttons

A straight source from CD player to Amp. will only be useful when there is a means to adjust the volume.   Some CD players incorporate volume controls on the remote which allow output adjustment.  I have used a Magnavox CDB-473 CD player this way, but there are challenges.

Magnavox CDB 473 with awesome sounding TDA-1541  chip and adjustable output using remote.

When first turned on the CD player would revert to full output.   If after turning the unit on and I put a CD in the tray hitting play to close the tray but forgot to turn the volume down then the opening track would begin at maximum volume.   I damaged a lovely Mission 700 Mk II woofer this way.  Another challenge is wondering if there was signal deterioration when turning the output down on the CD player.  So in theory a CD player direct to Amplifier can be a means to minimizing signal loss or contamination such as may occur with some pre-amplifiers.   An Amplifer with a output control on the front can be a means for controlling the volume when going directly from CD to Amplifier.  If you are like me you are unlikely to keep the amplifier adjacent to the listening position and will keep it equidistantly between the speakers to keep speaker cable lengths short and equal.   Having to hop up and down to adjust the volume will get old.  But if you don't mind keeping the system at arms length to the listening position and using longer speaker cables, then you will benefit from output controls for each amplifier channel to help maintain balance between channels and to maintain balance between upper and lower frequencies when bi-amping.

CD to Amplifier with a DAC (Digital to Analog Converter) in the signal path is an option to consider for optimal transmission of musical signals with minimal loss or addition.   Will discuss DAC's later.

Output options for the Magnavox CDB 473 allow both analog and digital options.

Convenience is typically king, so when using separate components the more common approach is to use what is commonly referred to as a Pre-Amplifier.   Basically a Pre-Amplifiers purposes are signal manipulation such as volume and balance and bass and treble controls (sometimes a mid-range control is thrown in), pre-amplification with a phono-stage,  and a source selector.  There are numerous variations on the above.   A "purist" using a Pre-Amplifier would likely settle for a volume control, possibly a balance control, and at least one source input and a amplifier output but for bi-amplification two amplifier outputs are nice though cable splitters can achieve the same goal.  A phono stage pre-Amplifer can be off board and connected to a line source input, but more commonly they are incorporated as one of several inputs on a Pre-Amp.  So if the "purist" settles for an on-board phono-stage they are likely to want an additional source to choose for use of a CD player.  I need to emphasize that a "purist" might not be feeling honest if they "settle" for more than a volume control and a phono stage.  Also a "purist" might insist on an off-board (out of unit) power supply to minimize risk of signal damage which the phono-stage is most at risk of being affected.

Rare Quatre Pre-Amp

Some self described purists are comfortable "settling" for more than Vinyl to listen to and welcome a line source input in addition to a phono stage.  I like experimenting to find a comfortable level of convenience versus risk of signal damage.  My main system includes a Mission 776 Pre-Amp that offers an onboard battery power supply with an volume control and a source selector with a phono stage and 2 line sources.  No balance, no tone controls, no filters, etc. but this is quite satisfactory for me.

Quatre Pre-Amp's variety of inputs and outputs.  Note the 2 Amp outputs allowing bi-amping. 

Rotel RC-870 controls offering Phono Moving Magnet or Moving Coil options

Rotel RC-870 beautiful backside

Typically a Pre-Amp will offer Volume, Tone, and Balance controls with a several source selector as a minimum.   A number also add a built-in Tuner and these most commonly include remote capability. Other Pre-Amps allow for various filters, multiple phono-stage options including various cartridge capacitance settings for Moving Magnet cartridges and often Moving Coil cartridge compatibility.

Some Pre-Amplifers add Multi-Channel compatibility for use in Home Theater Surround Sound systems. Saving this conversation for a later posting.  But I must throw in now that I am still looking for a Multi-Channel preamp that will compete with an average two channel preamp for sound quality.  Also the Multi-Channel preamps seldom include a phono-stage.   In other words, when using a Home Theater as a primary sound system, you might not experience the level of two channel audio quality you are hoping for.

A side note for consideration...  Tube Pre-Amplifiers.   Most sound good to most of the audiophiles most of the time, mostly.  If using a Solid State Amp, then the effect of a Tube Pre-Amp will likely be most appreciated.   Also a Tube Amp with a Solid State Pre-Amp seems to be a good balance, but I have questions about a Tube Amp and Tube Pre-Amp together becoming a little too gentle.  I dont have a Tube Preamp yet, just Tube Amps, so I dont have a answer yet.  By the way, Solid State Amps and Preamps used together can be wonderful too, even without Tubes...