Windows version and audio output types

[Chris Hartley]

I've yet to try the new windows installer but have been following the
threads and look forward to giving it a go on my next clean-down (a
chore performed with monotonous regularity).

Currently I am making daily use of the [patched] windows version of
this program to download audio which gives me a final output file type
of .m4a.

Before the program was patched (some several months ago) the final
output file type was .aac.

Unlike many who have raised the subject, I am not attached to a
particular output file type however two things about this change in
file type raise my concern:  I note that the .m4a always comes in at
128 kbps and yet the earlier pre-patched version of get_iplayer output
.aac files which were variable in terms of kbps and ranged between 131
kbps and 135 kbps.

Preservation of audio quality is important to me and therefore, since
the patched version I've had a nagging concern that the 128 kbps .m4a
files were possibly losing some of the original quality of the .aac
(but as a clueless windows user had no idea how to change this to
preserve the previous .aac format).

So my question is two-part:  a) by changing the audio output file type
to the 128 kbps .m4a, has the quality been depleted? and if so..., b)
is it possible for the novice windows user to change the audio output
type back to .aac if desired?