For quality sound recording, Zoom have two impressive products.
The Zoom H4n is the most versatile portable digital sound recorder
available at the moment.  It has a built in X/Y stereo microphones with
no phase shift, or you can plug in microphones via two XLR/phone input
jacks.  It records in stereo or 4-track mode up to 24-bit/96-kHz linear
PCM WAV files or as MP3.

I have been using the earlier model for about four years.  I tack the
sound onto video using video editing software.  For piano, I tape the
recorder onto a microphone stand about a foot from the partly opened
lid.  Here is a sample recording of one of Julian Dyer's rolls played
on my British DA foot-pumped Steck:
http://www.4shared.com/audio/UxRhhvpp/Where_the_shy_little_violets_g.html 

Zoom also make the Q3HD, a small video camera with the same X/Y stereo
microphones designed for sound buffs rather than video buffs.  With
this device you won't need to fiddle around attaching sound to video,
but you lose control of where you put the microphone unless you plug
one into the 1/8 inch stereo line-in jack.

Both of these devices have manual gain controls.

Regards,
Ian Sanderson