Mike,
Thanks for your comments. When I spoke of "compression" being
responsible for the horrid sound of many of today's analogue FM
stations, I was speaking of compression in the analogue sense, in
other words, dynamic compression where there are no soft passages and
no loud passages, everything is the same loud obnoxious level.

As far as your comments on FM IBOC being 96K, I was well aware of that
fact. The issue is that the digital compression algorithm that they
use is much better than "a 96K MP3" and appears to me to have the
audio quality of a 256K MP3 (some harshness due to the "Simpson's
Rule" effect, but good enough for automobile listening and background
music).

All of my statements were based on empirical listening tests comparing
the sound of IBOC in AM and FM mode to AM stereo and analogue FM on a
Marantz 10B tuner etc.

As far as your comments on the AM section of the Yamaha RX-V4600, I
think that it's a fair to midland AM DX tuner. If you read my
statement carefully about the Lansing MI station, I said that the
analogue signal comes in with excellent signal (20 to 40 dB over S9 in
ham radio terms), but the IBOC "subcarrier" is not detected.

Your comments on the audio quality of AM IBOC disagree with my
empirical listening tests though, I still think that the Canadian AM
Stereo station CFCO is far superior to any of the 3 IBOC stations that
I've heard locally.

In conclusion, I think that AM IBOC is not going to go anywhere and is
indeed really pesky in terms of the QRN that it spews out, but that FM
IBOC has the promise of success due to the "narrowcasting" that's
possible using the alternate channels. Luckily, we here in Detroit
are seeing the advantages of FM IBOC with very interesting and
appealing "second HD channel" broadcasting by 9 local stations.

Fred E.