Ok - and for the sake of completeness - the "blowing-up" of a Mono-Buffer to Pseudo-Stereo could have been done this way:

Code:
'a very short 16Bit Mono-Buffer with only two entries
Dim Mono(0 To 1) As Integer
    Mono(0) = 1
    Mono(1) = 2

'now we blow up and copy-over the Mono-Source to PseudoStereo
Dim Stereo() As Integer
  ReDim Stereo(0 To 2 * UBound(Mono) + 1)

Dim i As Long
  For i = 0 To UBound(Mono)
    Stereo(i + i) = Mono(i)     'fill the even entries
    Stereo(i + i + 1) = Mono(i) 'and the odd ones too
  Next i

'a controlling-output will show the correct sequence 1,1,2,2 now
For i = 0 To UBound(Stereo): Debug.Print Stereo(i): Next
Olaf