BBE 386 Acoustic Preamp

This unit is Transistor amplification.  This is designed to be used for an Acoustic guitar with a pick up primarily so it has only a 1/4" input.  According to the manual, this unit's max output is +18dBu, but it does say that this "may vary due to control settings."  All I know is that it is loud enough when I use it live or in a recording setting.   As for controls, you have "Gain" or course, then you have the "Low Contour" knob which adjusts the the low frequency (50Hz) by adding 10dBu or taking away 10dBu.  The next knob is the "Definition" which is the primary control of the "BBE Process."  This tightens up the Low end and improves the clarity of the High end, which in effect makes the whole spectrum sound clearer.  Next to that is the toggle switch for the Definition knob or BBE Process.  This is nice to have so you can A/B the sound and hear exactly what the BBE Process is doing to your guitar signal.  Next you have the EQ section which consists of a "Level", and a "Frequency" knob.  The first controls the level of the Peak Frequency and the latter defines that Frequency (500Hz-2kHz).  Next is the Notch filter section which consists of a "Gain" knob that adjust the frequency of the filter (85Hz-250Hz) and a button to toggle it off and on.  The only effect you are going to get out of this unit is a cleaner sounding guitar.

UTILIZATION

Yes, you can easily get a good sound out of this unit.  In fact, the moment you plug your guitar in, you will notice a difference, at least I did.  There are only 6 parameters to mess with.  Once you get the hang of what each one does, you will have no problem dialing in the right sound for your guitar. 
There is not Keyboard on this device, this must be a mistake.
Yes, the manual is clear and very sufficient.  When I first got this unit, I was unfamiliar with BBE products.  After reading the short (15 pages) manual, I felt well informed and ready to use the device with confidence.

SOUNDS

I use this with a Martin D-16 and a variety of Basses (Fender JP-90, Carvin 6 String Fretless, and a Peavey Soundgear).  The only sound you are going to get out of this unit is a well defined tone. I use this to reduce the mud from all the instruments I use.  I use it to brighten up my Martin D-16, its all mahogany so it has a very dark tone in the first place.  I love it for that, but sometimes I need it to be a little brighter to cut through a mix, the BBE Unit does the trick.  When I use it with a bass, the Low contour helps beef up the low end without dominating the rest of the tone. 
Yes, when you "zero" all the parameters out on this unit, it is very neutral.

OVERALL OPINION

What I like most about this unit is how wonderfully clear and present it makes my guitar sound.  What I don't like about it is that it has only a 1/4" input.  I wish it has a Mic input too for when I am recording with a condenser on the guitar, just to hear what it would do.  I got this unit used for $80 which was a great deal in my mind.  I don't believe they make this model anymore, so used is the only way its going to happen.  I give this unit a 10 out of 10 for sound quality.  I got this a few months after I first started recording on my own with a Roland VS 1880.  I used to just plug my Martin directly into the roland and the sound was always a little muddy.  After I got this unit, I notices a HUGE difference in the clarity of my tone.  I also have a ART MPA Gold tube preamp.  Its nice to have the option of Tube and Transistor.  They both serve there purpose well.  Yes, I would definitely buy this unit again.