Tube rolling Question

Hello Tube Rollers
I recently bought my first tube preamp (Blue Circle 21.1). I've noticed I am need of new tubes as the tube whoosh is considerably more noticeable now than 6 months ago. The amp comes with  Electro-Harmonix 6sn7 tubes which I appreciate and dig the sound. I will certainly replace these with a the gold pin model as I like the sound profile. Here's my question:

What other tubes might you recommend for a different "flavor" of sound, and just to have fun with. I am a poor audio guy so please no recommendations for tubes that will cost more than preamp. 

Thanks in advance. 
I've tried a bunch over the years. Save your money. There's differences sure but once you get past noisy/old to good/new I just don't think the remaining differences are worth much. Especially when you can get a whole lot more improvement from something like a Synergistic Research Blue Quantum Fuse or a set of ECTs. Either of which cost about what a set of tubes will run you but you get a lot more improvement and unlike the tubes if you don't like em you just send em back.
Electro-Harmonix 6sn7 sounds too bright.

I recommend you to look for Ebay dealer on NOS Silvania vt231 who offer return like this.

One recommendable choice of new production tube is
Shuguang Treasure CV181-Z .

It sounds sweet and balanced while NOS Silvania vt231 sounds more dynamic and detailed.

They are compatible with 6sn7.

These have very positive attributes and will not break the bank:

 A long time customer with Upscale, otherwise zero affiliation.

 You should give vintage GE or Sylvania a try. They can be had at very reasonable prices, so you can roll without spending a small fortune. BTW, I use all GE preamp tubes and I like them over others that I have tried!
Brent Jessee sells quality NOS vintage tubes. Here is a comprehensive description of the sonic signature of each brand of the 6SN7 tube.

My recommendation for a new tube roller would be to try RCA. Classic lush sonics with an open sweet midrange, very good dynamics. A 6SN7GTB is very affordable.

Amperex Holland are more expensive, but they make some cost effective types. Incredible 3D soundstage with airy highs.

2nd the Sylvania route. Also new production Sophia Electric 6sn7s are very good to my ears
Some good info can be found here: Having tried the top twelve on that list, I’ve been using the Tung-Sol, Round Plates and Sylvania 6SN7W, metal base tubes for years, with no desire to move. SO GLAD I bought a few, before the prices went nuts! Some, that provide almost all the nice attributes as those, but- don’t sell for nearly as much, are the 1940’s, bottom-gettered, Ken-Rad(JAN-CKR) and bottom-gettered, Sylvania(JAN-CHS), VT-231/6SN7GT tubes. The balance of those twelve(that I tried), were all too warm/colored(for my taste, anyway). Here’s a very reliable source:
I'm using the Tung-Sol Round Plates, 1940s and they are wonderful. But at $275 per tube for low noise low microphonic, it's a major expense.
I used the 40s Tung Sol rectifier tube with my Sylvania 6SN7 Bad Boys in the Woo Audio headphone amp with great success. I bought a matched pair of Tung Sols at no small expense just in case. Better safe than sorry. I also used two Herbies Tube Dampers per Tube, one on the glass the other on the base. Again, better safe than sorry. 
I consider spares indispensable.  I just hope my spares stash outlasts me.  I'd hate to have to miss a mortgage payment(proper priorities, and all).
Be very careful of any seller that sells "NOS in white boxes". What this usually means is that the tube tests as NOS but is most likely used. I am not sure if one respondent was suggesting that there exist 6SN7s that were made by Amperex but just for the record Amperex never made a 6SN7. I have seen Amperex branded 6SN7s but these were made by GE. Be very careful of tubes branded Sylvania Bad Boys. The Bad Boy is a great tube but is very specific in construction. Tall, 3 hole black "T" plates with bottom foil getters. Most I have seen were made in late 1951 and in 1962. This is the only Bad Boy made and many ebay sellers are selling Sylvania tubes as Bad boys which are not and quoting an online tube seller who knows (or should) better. Be careful.

An excellent inexpensive 6SN7 tube is the GE short bottle, side getter. Read what Brent Jessee says about them. He makes a comparison to an extremely pricey tube. A friend has a Blue Circle preamp and uses that GE as it was his favorite from all he tried.

Great guidance and directions!!! Thanks One and all. You've given me a lot to look in to. 

Much Appreciated

Happy listening !
I have a pile of 6SN7GTBs as my amp (uses one) and preamp (four) use 'em. From new Tung Sols (these seem to require some break-in but do eventually sound reasonably neutral) to NOS GEs, Sylvania "chrome domes," possibly re-badged Amperex tubes that still sound fabulous (my Dennis Had amp was supplied with one of those and yeah...its internals are exactly like other non Amperex tubes) etc, and they're all relatively inexpensive and plentiful. You simply have to experiment to see what sound floats yer boat.
I like the EH 6SN7 but gold pins offer no advantage IMHO.
my friendly advice would be to seek vintage soviet 70's era 6SN7 tubes, your preamp was designed with russian tubes so most likely will sound the best with same kind but from different era. Normally this is the case no matter how much tube rolling we do. 
Ideally a particular amp design should be totally Tube brand independent. All 6SN7s have the same electrical characteristics. Unless you wish to ascribe Golden Ear status to the Ruskies. I will eat a bug if ANY Sylvania or RCA or Tung Sol 6SN7 doesn’t sound a lot better than ANY Soviet 6SN7.
Hi geofkait, most probably and ideally they should sound better but if synergy comes to the mix they will probably don't. As for golden ear status please be open minded and open eared, no biases in audio, try, try, try and try. The best example is in the E88CC family where the finest sounding ones (and a lot cheaper) are 6N23P from the 70's by far. This is my experience after trying every possible NOS (still having more than 300). Most NOS are a waste of time (educated though), money should be spent on LP's.

Your star has descended behind the bog.
Synergy? Give me a break! The Ruskies won’t take umbrage at what I’m about to say because they don’t know what umbrage means. But the Ruskies don’t experiment with various brands of tubes. They just use whatever tubes are left over from the last MiG-25, The Ruskies are known for using the cheapest parts they can get and still get the thing to work. I was in the pink building with no windows. They weren’t making doughnuts 🍩  in there.
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@petg60- In over 40 years of paying close attention/listening to tubes, and the opinions of those intimately involved; the ONLY small signal, Russian-made tube, I’ve ever seen mentioned(either octal or nine-pin/any family) in any comprehensive comparison, is the 6N23P. THEN, ONLY Reflektor’s SWGP, silver shield,1974-75 iterations, hit the top ranks. Those of other makers(ie: Voskhod), years and construction methods, varied greatly. Production of the really good sounding ones, was limited to an extremely narrow time frame. Once the sound was discovered, most NOS examples, of Reflektor’s star iterations disappeared, quickly. Of course; you brought up the 6DJ8/E88CC family of tubes, in which there have been a plethora of excellent tubes, manufactured over a couple decades(50’s and 60’s/Siemens, Telefunken/Amperex, etc), and still obtainable(though expensive). Try finding any of the good sounding 6N23P’s now, at bargain prices. I tried to find some, for my CDP, to try against it’s six Siemens(early Sixties/grey shield) CCa’s. No luck/unobtainium(at anything resembling a reasonable price)! The really good/very rare Russian versions, were a flash in the pan. Back to the 6SN7 topic: let’s hear about ANY Russian version, that’s ever been favorably compared, in a NOS shootout. Of course; as subjective as listening tastes are, as varied our systems, rooms and aural acuity- no one can EVER say, what’s right/best for anyone else. One can only listen/experiment, for themselves, limited by what they’re willing to spend, in time/funds and/or, how badly they desire excellence(whatever their perception), in presentation.