Retubing dilemma

I have a melody el34 integrated amp.  As I mentioned in a older thread one of the tube store el34 preferred series tubes went up in flames. So now I have a choice and I want to see what people think would make the most difference sonically. I would like to keep this under  $200. 1.  I currently have 2 northern electric 6Sn7 tubes and 2 shuguang treasures 6sn7 tubes, 1 of each type on each side.  Should I replace the northern electrics with shuguangs so I have a full set all the same and just replace the el34 with the same preferred series or
2. Replace the el34s with gold lion kt77 that seem to be very well liked. 3. Other suggestions. 
As an aside if I went with #1 should I move the old shuguangs to one side and put the new pair on one side. 
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There’s a lot of good information here, regarding 6SN7 tubes:       Far as whether you should have two of the exact same iteration/manufacturer, in each amp: pay particular attention, to the third from the last paragraph.
Rodman thanks very good link
Thanks millercarbon. I will look through your posts. Were you suggesting the JJ EL34-II or plain EL34? Have you tried the GL KT77?

Rodman thanks for the great post and clearing that up for me. 
I read the article, WOW it’s out there. This is how people that make music do things, really, they mix valves to get their signature sound.

That 3rd from the bottom, paragraph is surely not meant for the audiofiler.
Someone seeking superior sound. It’s not gonna happen, mixing valves left to right, not matching top to bottom, and most of all mixing brands left to right.

It is a weird valve to begin with, from a Marantz / Mac perspective, Cary was the big user and promoter of that valve.. Personally he voices with TV tubes in my opinion. The exception was his selection of Ruby EL34 valves. That is a wonderful valve.. Things like 6SN7, and EL84, and 6922? HUH?

Don’t compute. You better do something with those valves.. There is a LOT better valves. The weird thing is, some manufactures VOICE with cheap valve for a reason. It’s like saying they come with the right power cord, from the factory. LOL A lot of PC still have the vinyl hide drying on the 1 dollar PC. NEVER meant to be used. Valves are very much the same way....

BTW MC JJs are Comrade Ivans, favorite...:-) Don’t get all huffy now.. LOL. your gonna be amazed if you move into a great set of valves.. NO they don’t have to cost over 200. USD either. More like 100. for a set.
GL (200. or more 5% match), Solvex, PSVANE (200. or more 5% match)

But EL34. A lot better sounding is EH fat boys are real nice and Green print BOTH EH. GL, KT77s good but spendy.. The EH is as good. and matched better. 5% not 10% like GL, Ruby, I can’t say a bad thing about that valve.. Made in China..Great reputation... NOS, save your money, unless you have a great friend (power valves) 1000. Mulards NO....

Small valves, great NOS stock, a lot better than what you’re using...
But not big bucks...

My insurance guy has Melodies, I say Melodies because he has 3. Two are 6L6 one is KT88/6550.

He learned about cheap 6L6 valves.. hee hee, scared the crap out of him, calling me at 12:30 at night...LOL Tube red plating and noisy as all get out... Comrade Ivan sent him 100 valves for 3-4 usd a valve. UPS....40% were under 10% of a standard RCA 6L6 (64). A lot of testing for me, though (up my rates)...:-)

Realize that you have an EL34 amp . That said one of my integrated amps is an Ayon Audio KT88 ; to my ears Gold Lion, Psvane , Black Treasure and Sophia Electric tubes all sound better than JJs , and just as reliable.