What's the best 6NS7 tube you have tried in your Atma-Sphere MP-3 preamp?

I don’t have an Atma-Sphere preamp, but I do have four different integrated tube amps that run 6SN7 as signal tube and/or driver tube in preamp section in front of EL34, 6550, 6L6, KT-88, 300b or 845, power tubes depending on the amplifier.  I have amassed a ridiculous (as in $2k)  collection of almost 100 used, NOS, and testing NOS 6SN7s. Here’s how I would rank them in my systems:

1. Sylvania short bottle chrome top 6SN7W from 1945. Best bass, midrange, treble and detail. Simply the best I own. Very rare, very expensive. 

2. Tung-Sol brown base 6SN7WGTA 1962. Detail king, great bass, midrange and treble extension, just not quite as magical as the Sylvania above, but a beautiful sounding tube.

3. Tung-Sol black bottle round plate 6SN7GT. Deep extended bass, lush midrange but treble lacking a bit. Not as detailed as the WGTA above. Also very rare and uber expensive, probably not worth the $ in the end. 

4. tie Sylvania 6SN7GT “bad boy” T plate, 1951; Tung-Sol 6SN7GT T plate construction same as Sylvania bad boy. Tung-Sol has more detail, but both are very linear with excellent bass, midrange and treble extension.  “Sweet” sounding tubes.

5. Raytheon USN brown base 6SN7WGT. A workhorse tube, very clean, linear, detailed tube that sounds like it could live 10,000 hours. Not as magical as those above, but one you could listen to and never tire of. Tight base, balanced midrange and treble.

The rest - RCA grey bottle VT-231, very smooth, sweet non-fatiguing tube, another one you could listen to and never tire of. GE 6SN7GTA from 1955, an underrated bargain, very detailed, excellent bass and treble extension, midrange a bit muted, but still a great sounding driver. Finally, the super bargain Russian Foton 6H8C from the mid-fifties. I paid $32 for two pair. A good all-round tube that doesn’t stand out in any category but doesn’t disappoint either. Musical linearity defined. 

For some reason the moderators took down my previous post so I’ll try this again.

I tried 4 different pairs of different makes and brands of 6SN7 tubes and the synergy with my MICROZOTL MZ3 Headphone Amp / Preamp / Integrated Amp with the Sylvania 6SN7GT Bad Boys and/or Sylvania JAN-CHS-6SN7GT Bad Boys are some of the best sounding tubes I’ve ever heard. So I finally settled on the Bad Boys. These are the key distinguishing features to recognize a Bad Boy tube.

1) 3 hole black T plates

2) Bottom getter flashing 1/3 way up the tube

3) Shiny silver top and bottom rectangular mica. The top mica has three small triangular edges bent down on each side.

4) Copper grid posts

5) Date code of 2xx(or possibly 1xx or 3xx) were 1, 2 or 3 represent 1951, 1952 or 1953 and xx represents the week.

6) Full black bottom base with Sylvania 6SN7GT and/or Sylvania JAN-CHS-6SN7GT in green letters. And yes the Sylvania JAN-CHS-6SN7GT with full black bottom base with green lettering are also Bad Boys. So you’ve actually have two options here.

7) Look for the tall bottle versions only.

‘JAN’ stands for ‘Joint Army-Navy’, and was meant to indicate that the tubes labeled as such were ‘passed’ for military use. However, no additional criteria that were not already fulfilled by the 6SN7GT specification were known to have been imposed. ‘JAN’ labeled tubes are identical to non-JAN tubes of the same vintage and construction.

Sylvania 6SN7GT and the Sylvania JAN-CHS-6SN7GT Bad Boys [3 holes in each plate, copper grid posts, bottom getter, green labels, black base and plates, vertical date code (read from top-down) ‘2xx’ with ‘xx’ representing week #, ’polished’ silvery rectangular mica]

The Sylvania 6SN7-GT and the Sylvania JAN-CHS-6SN7GT Bad Boys was made from late 1951, week 39 ("1/39") to early 1953, week 13 ("3/13"). They have black T-plates -3 holes, Copper grids, Bottom getter, "polished" rectangular mica, green labels on black base.

I haven’t heard any of the Chinese tubes recommended by Don Sachs, though I’m tempted now. ;-) My go-to 6SN7’s for both my Williamson amps and my Aikido preamp, are:

1) GE 6SN7GTA or B. Well-made, non-microphonic, consistent. Open, textured sound. Can be had new or test-like-new for around $50.

2) Sylvania 6SN7WGT, with parallel (not angled) plates. Beautiful midrange. Around $75-100 each now, but people pay a lot more than that for new boutique varieties.

I currently use the GE’s in the amps, as they are a bit more neutral, and the Sylvanias in the preamp. It’s a nice combination.