Phono preamp tube rolling.

I have a Zestos Andros Deluxe 2 that I've done a fair amount of tube rolling in.  The Zestos has two 12AX7s in the "primary" spot, and an interesting pair of 12DW7s (one triode has an 12au7 like mu, the other having a 12Ax7 like higher mu), which according to Zestos drive the dedicated output transformers.  I've rolled both positions, the 12 DW7 makes only a slight difference in clarity.  I've tried Mullard 12DW7s, some American NOS ones... not much difference to be honest.  I put in some NOS Orion DW7s (made by Tungsram) cause they look the coolest and I convinced myself they sound the best.  : ) 

The 12AX7s do make a pronounced sonic difference though.  In lieu on the stock JJs,  I've tried several NOS including: Telefunken smooth plates, Tunsgram 12AX7, RCA black plates, Mullard longplate square getters, Amperex long plates D getters, and Tesla E83CCs.  Long story short, the best sound came from the Teslas and the Telefunken in terms of clarity, bandwidth and detail.  Close behind were the Tunsgrams, which although deviating from neutral, had a seductive bloom to them.  The RCA black plates fared surprisingly well with a punch and clarity that I could've lived with.  The Mullards sounded like a wet blanket over the speakers, and were not suited for this phono amp usage.  All tubes were very quiet.  I'm leaving in the Teslas.  BTW, I love this phono amp.  It frankly far surpasses the Pass XP15 that preceded it in all areas.  The Zestos is completely quiet, with no overt tube noise.  It's end game for me.

mulveling-- Those Mullards, despite their lore and hype, have never really found favor for me, either as gain tube in my Rogue ST100, nor here in the Zestos. I paid a fair amount for them, and really wanted to like them, but I suppose my ears and system don’t really need to be fattened up by the Mullards. : ) If I need thickening, the RCA black plate will achieve that, with no compromise on bandwidth.

I am indeed smitten with the Zestos, but it is my first tube phono amp, so I am new at phono tubes. It is just beautiful all around. I got a good deal on it here at Agon and jumped on it. I’m REALLY glad I did. Insert your audiophile cliches here: "veils lifted...." etc. : )

BGRP - Black Glass Round Plate. I have a pair of 12AU7s Tung Sol black glass (grey standard plates, I think) that sound fantastic, with great extension, but they are lowly 12AU7s: )