If you are still using BASS.NET 2.3.x then the signature of a DSPPROC is different - as written in the documentstion!!
In 2.3 its:
Private Sub NormalizeDSP(handle As Integer, channel As Integer,
buffer As IntPtr, length As Integer, user As Integer)
and you would have to set the DSP via:
Bass.BASS_ChannelSetDSP(_stream, _myDSPProc, 0, 0)
No eMail unless you read the docs :-)
However I suggest you upgrade to 2.4 anyhow, since 2.3 is not supported any longer.