what tubes to use in manley steelhead rc preamp

Yes I use Manley supplied tubes

Do you have any good sources for the tubes for your Steelhead?

My use of the 5687/7044 variety tubes has been the different than Rgurneys. I like the GE7044 better than any other 5687 type tube but the Bendix 6900. I have never had noise issue with them at all. I've used them in CDPs, headphone amps, and my Manley amps I use now. At less than 20.00 a pop you should try them out.

The Steelhead uses the 6922 and either the 7044 or 5687. The 7044 tends to be microphonic. A better choice would be the 7119 of which the best is Amperex, now becoming quite scarce. Many like the 5687 instead, of which the Tungsol black plate is considered the best. For the 6922, there are many NOS choices to consider. Among the new production 6922 tubes, the JJ is quite good, IMHO.
In my Steelhead, I used the Siemens Cca 6922 and the Tungsol black plate 5687, although I also like the Amperex 7119 as a different flavor. Good luck.