I have two pairs of the RCA gray glass VT-231s, and one pair of the RCA gray glass 6SN7GT. The VT-231 pairs are indeed a bit microphonic. The GT pair is not, and are dead silent! I honestly could not tell of any sonic differences between the two, and yes, the GTs are cheaper than the VT-231s. The GTs are on my Oppo-95 now. Glorious!
I am using the Genalex Gold Lion GZ34, which I got off of Ebay for $40 from "tubemazestore". It's really a very nice rectifier though its current production (What?? Not NOS?? Sacrilege!
). Great match for the RCAs above.
I have tried and wanted to like the Mullard GZ34 (I own the F31 date code) based on its reputation. I could never warm up to it. It always ends up back in its box.
I will eventually try a pair of short bottle Sylvania 6SN7W chrome tops on the Oppo, but with the RCAs in there now, I really am in no hurry!
Currently listening to the Acoustic Blues channel on Pandora thru the Oppo. Damn, it sounds good!
The RCA grayglass are said by tubeworld to be slightly microphonic, but are relatively inexpensive for premium 6SN7's (~$100/pr), compared to $250-500/pr for the tubes David is recommending.
I'm going to be trying the Sophias with a Mullard GZ34 rectifier next, currently using Sylvania "Bad Boys" with that Mullard, certainly not "forward" or "harsh", more "airy" with what I would consider an average soundstage. Good bass with this combination!
Which Gold Lion rectifier are you using? I'm a relative tyro, and the only Gold Lion I find easily is the superexpensive 5U4G?