AVR-Chat

Hello!

I had some fun today and wired up my Mega 16 to a D/A converter.  
Knowing that it would probably sound terrible, I hooked up an audio 
signal directly to the Mega 16's A/D converter, and the output from 
the D/A converter directly to my mixer.

Although highly digitized, I could kind-of make out the songs.  Part 
of the problem could have been that I did a 10 bit A/D conversion and 
tossed out the lowest significant 8 bits.  Another part may have been 
that I'm running into a 12-bit D/A converter on the output (of which
I 
hooked up to the most significant bits).  BUT, after some 
contemplation, maybe I also cut off 1/2 of the audio waveform, the 
part that goes negative, in the process.

I'm going from an audio signal, straight into the Atmel Mega16's A/D 
converter, then out into a DAC7625 (12 bit parallel D/A converter).

Here's my bascom program:

$regfile = "m16def.dat"
$crystal = 4000000

Config Adc = Single , Prescaler = Auto , Reference = Internal
Start Adc

' Set all port c pins to output.  The output of port
' c's pins go directly to the D/A converter.

Ddrc = &B1111_1111

Dim Cv1 As Word

Do

   Cv1 = Getadc(0)
   Shift Cv1 , Right , 2
   Portc = Cv1

Loop

Here's my question.  What are my next steps?  How does one manipulate 
the audio signal before feeding it into the A/D converter to get the 
best results?  If I take the output of the D/A converter, it's going 
to be 0 - 2.5 volts.  As far as I've seen, audio signals have both a 
positive and negative element.  How can I take my 0 - 2.5 volts and 
spread it out over -5 to +5 volts?

Thanks!  I know this is a total newbie question.  If anyone knows of
a 
good website that answers my questions, please let me know.  Direct 
answers are always appreciated too!

- Bret