If you are doing this test with low Tap
settings, you may want to look at the response
with a spectrum analysis program before concluding
there is a real problem. With a low number of taps,
the DSP filter may become like a comb response
with multiple peaks off the primary response. These
can fool your ears depending on what the spectrum
response is. It may sound like filtering is "wide
open" to your ears, when in fact it is not. This
applies both to single 10 Hz BW changes and to
single Tap setting changes. One small change can
sound very dramatic to your ears.