I jave an S70 with the SC816 cd/radio/tape. The CD spounds pretty good.
The radio, another story. Stereo seperation is poor, high frequency
response limited and no dynamic range. It sounds flat (especially
compared to the CD).

My antenna does not always go up and turning radio off and on will
send it all the way up. This is common on my car and causes poor
reception.

There are some "hidden" functions on the SC816 that may help. Lifted
text after google search on "volvo sc 816 hold":

To set the ASC (its
adjusts volume in relation to road speed - note not engine speed) you press
and hold the CD button (the one furthermost to the left - there are 3
buttons above the tone - treble, bass and fader controls) down until the ASC
appears in the top rhd corner of the radio display.

Switch ignition to position 2
Turn radio on, and select FM mode
Turn radio and ignition off.
Continue holding butons until SRC is displayed.
Press the # 4 preset, to turn this option off.
The factory setting will be restored if the battery is disconnected or the
radio is removed.

I think SRC is something to do with the way it trys to switch in and
out of mono, set high frequency limits, etc. -- Anyone have more on this?