Hello -- The only Welte recording that I am aware of is of a number
of rolls of Gustav Mahler's music played by Mahler himself.

There are four rolls; three are first played alone and are then
played again as accompaniment for a singer:

1.  "Ging heut' morgens ubers feld"
2.  "Ich ging mit Lust durch einen grunen Wald"
3.  Fourth movement Symphony No. 4
4.  First movement Symphony No. 5

The singer for the first two songs is Claudine Carlson, Mezzo Soprano,
and the Fourth Symphony excerpt is sung by Yvonne Kenny, Soprano.  The
disk also contains an oral history by people who knew Mahler.  It is a
product of the Pickwick Group Ltd. and the number is GLRS 101.

The same recording can also be found on a two-disk set from Conifer
Classics BM652.  This set also includes the remarkable recording of the
Second Symphony by the London Symphony Orchestra conducted by Gilbert
Kaplan.

Also included is an interactive CD-ROM pictorial survey of many
photographs and paintings of Mahler.  One is warned that this
presentation is playable on most, but not all, Macintosh and Windows
computers.  Unhappily it does not play on my machine.  Hope this
information is of some help.

Regards
John Johns