The Bugle Boys should be very nice. Try any combination you like, but I would do any changes in pairs- swap the first tube in both channels with 2 of the Telefunkens or Amperex, so whatever tube you use in one channel you are using the same tube in the same spot in the other channel.
Tube mixing for Preamps
I have just one a bunch of tubes of of Ebay and also collected some from an old electronics vendor in Vancouver. The preamp I own is an old BAT VK-30 which utilizes 6 - 6922 tubes. I have a great mix if tubes but only have a qty of 6 in the Holland made Bugle Boys while the rest are 3's, 2's etc etc. The most notable being the 3 Telefunkens, 3 Amperex Gold pin, 2 Gold dragons, 4 Audio Classic premium 6dj8/E88CC and other odds & ends. I know the Telefunkens are known to be the Cream of the crop for this type so it would be ashame if i did not use them. Can any of these be combined for use in my preamp or will there be unforseen problems using slighlty varying specs from each given tube that I mentioned? yeah I could try to finish off the set of Telefunkens but prefer not spend more money at the momment. I have to admit the bugle Boys are a step up from the 6H23's I just replaced.