Different Tubes and general purpose?


I’m trying to get a better midrange push or clarity out of my Line Magnetic 501ia tube amp.   Can someone help me understand what the specific function each type of tube performs in a power amp?  

I would like to upgrade several or all of my “stock” tubes but would like to understand where to start to beat enhance each aspect of the sound spectrum.   On my 501ia i have 4x KT120 and i believe those are power tubes, but please help clarify if wrong.  There are 2x 6SN7EH 1x 12AU7 and 2x 12AX7 (but the AU7 and AX7 look interchangeable to me).   As i look to upgrade where to i look to start, and why?  
Thanks in advance for help. 
gunners01
Saying "upgrade" does not make it upgrade. Changing tubes is not upgrading anything. Differences between tubes are slight or subtle at best. Someone here will jump on this so have to say yes there are differences. In the big scheme of things though you will hear much more difference changing the fuse inside the amp than changing the tubes.

That is to be taken literally. The difference in midrange clarity and detail from a $160 Synergistic Research Orange Fuse is a lot more than any tube you can find at any price anywhere. Don't take my word for it. Try one and send it back if you don't like it. No tube anywhere let you do that.

Then before messing with perfectly good tubes on a perfectly good amp look at Cones, power cords, contact cleaners and conditioners. There's a whole long list of things to do all of which will be far more effective than tube rolling. Which is by the way what its called. 

Tubes are not even that big a deal even within the tube amp itself. Transformers are far more important in determining the sound. Caps and diodes, as well. Tubes though are easy to plug in and out. They can be changed. So audiophools change them. Because they can. Which is exactly as good a reason as it sounds- no reason at all.
Tubes though are easy to plug in and out. They can be changed. So audiophools change them. Because they can. Which is exactly as good a reason as it sounds- no reason at all.
The same apply to FUSE?
Thanks millercarbon.  I ask as I’ve read plenty of articles about how there was notable, not step change, improvement in overall sound quality.   I get that that a lot audiophile purchases can either be snake oil or nearly inaudible changes.  
I have spent, at least in my world, a decent amount of $ on my system.  I’m largely pleased but I seam to be chasing the perfect balance and execution of several instruments in certain songs that seem to be not as crisp or prominent as i know they were recorded.  I would like to explore “tweaks” (i guess not upgrades) to my equipment that I’m hope can help me achieve what i want, without wholesale swapping out of equipment.  
My Harbeth HL5 plus sound incredible (coupled with a sub) on several albums (Fleetwood Mac, Tom Petty, New Order - Movement, the smiths - Hatful of Hollow), but on others (Big Country - the Crossing, or Led Zeppelin - 1st album) they seem to fail in the a really crisp and distinct mid range.  I could be the recording, but then again it may just be that these are speakers better suited for classical or jazz.  I was trying to explore other system changes to tease out more. 
The KT 120s are the power tubes. The 6SN7s, 12AU7s and 12AX7s are small signal dual triode preamp tubes, even though the 6SN7s look quite a bit different from the 12XX7 tubes. There are differences between the 12XX7 tubes even though they look the same. Don’t change tube type without checking with the manufacturer first. They’re not interchangeable. Sometimes there are variants (say of a 12AU7) that can be substituted.

Millercarbon likes to make pronouncements from on high rather than relate his experience as just that, his experience. He thinks that what works for him is the only correct thing for anyone else to do. Don’t let him throw you.

I’ve never heard your amp so I can’t really advise you on what to do next, but I can say that changing all the tubes could make a serious difference in the sound you’re getting, if you get the right tubes. You may also get the sound you want from only changing some of the tubes. Listen to your amp for a while to allow it to burn in and for you to decide what changes in the sound you would like to hear, although it sounds like you’ve already done some of that.

The place to start would be the manufacturer or his US distributor. Manufacturers generally use current production preamp tubes because they can’t get enough quality vintage tubes to fill their needs. Vintage tubes usually cost a lot more too. Everyone uses new production power tubes. There are different power tubes to try, though. Most people involved with tube gear try vintage preamp tubes in their amps, though, and are willing to share what they’ve learned with their customers. So if other Line Magnetic owners don’t chime in, give the US distributor a call.


There are a number of tube sellers who may be able to advise you. I’ll list a few, just google the names.  They'll talk to you for free.  Don't buy a bunch of tubes till you've got at least a couple opinions.


Vintage Tube Services
Jim McShane
Brent Jessee
Upscale Audio

Good luck, enjoy!
Great comments and advice from @tomcy6 . I'm a firm believer that each type of tube and each manufacturer has it's own sonic signature. Typically, you don't need to swap all the tubes from stock to vintage, aka NOS tubes (New Old Stock). There are specific tube locations which have greater influence on the amp's sonics. Most of us start with the small signal tubes, but you need to know the function of each tube in its location. Sometimes the user manual will state the function of each tube stage; eg, preamp, amp gain stage, or driver stage. Contacting the manufacturer or dealer is a better way to go. I won't give any advice on tube selection since I don't know your amp and since you're still getting to know it. 
I'll cite one example of a tube which provides an increased emphasis on the midrange and has plenty of "air" in the highs; it's manufactured by Amperex. Some tubes will be more linear, some will add detail to music, some will add warmth, etc.
Here's a primer on tube sonics of different manufacturers and each tube type; You can click on 12AX7, 12AU7, 6SN7. 
http://www.audiotubes.com/12ax7.htm

A member who is familiar with your amp very possibly will chime in.

 I disagree , Differences in tubes can be very noticeable.
A perfect example is a Telefunken 12AX7 vs Mullard 12AX7 is Very noticeable. I have tried many 6SN7 and found very few to have any decent bass. That was verified by Andy of Vintage Tube Services.
The only Vintage 6SN7  with good Bass is the Ken Rads ,but 90 %  are Microphonic, or another with Bass is Tung Sol Black Plates(not sure of the year). The Sylvania 6SN7 has great Mids and highs, but is lacking in Bass. i have not tried New Production 6SN7s
Call Andy  616-454-3467
. tell him your amp . He can help, i promise. Maybe tell him which tubes in  which spots V1.V2, V3 ..etc.
Let us know how it turns out
At this time I have a tube preamp which takes 2 12ax7's in the line stage and 2 12ax7's in the built in phono stage.  The 5751 is a direct replacement for the 12ax7, and the 5751 has slightly less gain.  I have used 5751's in the line stage and it can be a very pleasant addition.  I don't believe the 5751 is good to use in the phono stage as the extra gain of the 12ax7 is generally preferred.

In my experience there is a large difference in using 5751's versus 12ax7's and large differences within the brands of each type of tube.

Although it does not appear to have been updated lately, there is a lot of great information about the sound of different brands of mostly vintage tubes on Joe's Tube Lore  https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html
Tube gear manufacturers tend to supply their products with decent sounding, but lower cost tubes that they can procure a large enough supply to fulfill new orders and to have backup tubes for customers wanting them to supply replacement tubes.  Availability and price are key considerations.  That is sensible because any more exotic and pricey tube MAY, but not necessarily will, improve the sound--improvement is a matter of taste and system matching.  That leaves it up to the buyer to decide whether a particular alternative is an improvement.   Ultimately, it comes down to the owner having to either purchase or borrow candidate tubes to listen to the results.

Because trial and error is really the only approach, I would recommend starting with the cheaper small tube types.  If you are new to tubes, go slow and enjoy your amp for many months before attempting to change the sound through tube swapping .  It takes time to become familiar with the sound so that any change makes an obvious difference.  Also, expect to make mistakes--where a change initially sounds good, but in time turns out to be the wrong move.

Most people who have been around tube gear a while can pretty readily hear differences between tube brands and models.  Like any form of connoisseurship, experience matters.  If you are new to wine, it is hard to distinguish, much less reasonably evaluate which is better, without experience and experimentation.

Good luck.
Thanks all for the practical advice.   
I’ve had my amp for 2 years now and it probably has 50-60 hours of use, so I would have thought it is been broken in.  I will call my distributor and ask what he thinks in terms of where to start on rolling any tubes.  I’m not in a rush, so I have time to play around. 


Tubes will make a big difference. All you have to do is swap in some NOS tubes from back in the 50's or 60's to more current production tubes and you will hear why these NOS tubes are superior. As one of the prominent vintage tube seller's said, "I would rather have a good amp with great tubes than a great amp with merely good tubes." 

Anyone who tells you to use fuses, powercords, or conditioners in place of changing to superior tubes is giving you misinformation. Don't get me wrong, those things can give you some improvement too, but really good tubes speak for themselves. You should give it a try. IMO.
gunners01

I have the Line Magnetic 518IA integrated , the power tubes in mine are 845s versus your amp's  KT120s. I left in the stock 845 but changed the 6L6s to NOS GE, the tube rectifier to NOS RCA and the 12ax7s to NOS Tung Sol 5751s. The NOS tubes took the sound of the amp to a more satisfying level. For me, I found the lower gain of the 5751s more pleasing in the 518IA. Others have noted some NOS recommendations for 6sn7s, if you want to try new production I'd suggest either Sophia Electric 6sn7s or Black Treasure CV181s; I have used both in my Modwright LS100 preamp and found them quite good sounding. Per jetter's post it would be worthwhile to you click the link and  read Brent Jessee's assessment of the different individual tube types and their respective variants. So while I disagree with millercarbon's assessment of tube impact, I will agree with him that a quality power condition and cord, and isolation feet and so also benefit my equipment. I haven't gone the fuse route so I can't comment on that one way or the other.





























































































































































Facten thanks for the constructive help.  I have had a nice power conditioner for a few years now and have noticed a small improvement...really just eliminating any very faint background noise that might otherwise degrade or mute certain frequencies.   I have not invested in a new power cable, but will explore that at some point in time. 

Your advice on tubes is hugely helpful and I’m very grateful.  
Once again millercarbon is wrong. I wouldnt call attention to this if it werent for his hubris and his constant Synergistic Research schilling. 

I am a fan of power conditioners only if you have power which is problematic. Further, I have never tried a power conditioner that didnt take me one step forward and one step back. I am more a fan of reducing noise using a passive device or a good isolation transformer.


gunners01-
Thanks millercarbon.  I ask as I’ve read plenty of articles about how there was notable, not step change, improvement in overall sound quality.   I get that that a lot audiophile purchases can either be snake oil or nearly inaudible changes.  
I have spent, at least in my world, a decent amount of $ on my system.  I’m largely pleased but I seam to be chasing the perfect balance and execution of several instruments in certain songs that seem to be not as crisp or prominent as i know they were recorded.  I would like to explore “tweaks” (i guess not upgrades) to my equipment that I’m hope can help me achieve what i want, without wholesale swapping out of equipment.  
My Harbeth HL5 plus sound incredible (coupled with a sub) on several albums (Fleetwood Mac, Tom Petty, New Order - Movement, the smiths - Hatful of Hollow), but on others (Big Country - the Crossing, or Led Zeppelin - 1st album) they seem to fail in the a really crisp and distinct mid range.  I could be the recording, but then again it may just be that these are speakers better suited for classical or jazz.  I was trying to explore other system changes to tease out more.

The components you have are fine. Especially the amp, which haven't heard but certainly is highly regarded. Guy in your situation, almost always better to pursue optimizing what you have rather than trading. Because what you will learn if you do this long enough, its always possible to elevate performance more with a few hundred in tweaks than you can ever get with even a few thousand in a different component. 

One thing you said has me concerned, or gets my attention. 
I’m largely pleased but I seam to be chasing the perfect balance and execution of several instruments in certain songs that seem to be not as crisp or prominent as i know they were recorded.

Being largely pleased is good, and a strong reason not to upgrade but to tweak instead. But "not as crisp or prominent as i know they were recorded." Two things wrong with that. One, you can't know. And two, it doesn't necessarily have to be the recording. Click on over to Better-Records.com you will find a whole business dedicated to just what I'm talking about. 

You're thinking of changing something in your system. Your system is the same for every recording. But you're not talking about every recording. So its not likely your system, is it? 

Also one of the biggest most common mistakes people make is trying to make a song or recording sound the way they think it should. This is actually the exact opposite of what they should be doing. The very best a system can do is.... nothing. It should pass the signal, amplify and reproduce, whatever it is. No editorializing! Every recording should sound different. Completely different. No two the same. Its a founding principle found in tomes like from Robert Harley and its a founding principle of my system. https://systems.audiogon.com/systems/8367  Its in the description. 

But improved midrange presence and clarity are always good. So what you do is get some fo.Q tape. https://www.ebay.com/p/1358280415 Synergistic Research HFT are even better but some audiophools get triggered when the best is recommended over and over again, even though it is the best, so we will switch it up a little. Besides the tape really is amazing AND it more perfectly matches your midrange crisp and prominent quest. HFT are more across the board improving clarity everywhere from extreme low end to the top. fo.Q tape is more focused on eliminating micro-vibrations that muddle up the midrange and treble, revealing fine detail in a very natural way.

One thing that's been noticed with those same recordings you mention, they tend to sound really good right up until it gets loud with a lot of instruments and singing all together and it all starts to congeal. Used to think this was just the way it is. Well, turns out not really. The difference, what cleaned it all up, wasn't component upgrades. Wasn't the Herron, wasn't the Koetsu, nor the CTS cables nor even the HFT. And for damn sure it wasn't no tube. It was a tweak. 
Wow, way down here..  I haven't used your particular amp.  But I have heard The 805. quite a few times.. From the stock tubes he went to
RCA and Amperx (vintage) both improved the bass and low mids. Amprex better all round. He used Sylvania too. A lot more sparkle to that valve. Better highs for sure. NOT BRIGHT.. Tame sylvanias with good copper wire...

I have used countless others. Mac. VTL, CJ, DIY, ect.  Matched signal tubes can be quit a sonic nugget, if, they are not matched well to begin with, or have degraded.  L/R.

The big tubes, Unless there is a problem, USE them..KT120 hefty valve.

Again matched tubes go a long way on how a STEREO amp sounds make no mistake about it.. depth, clarity and cleaner phantom speaker resolution. 

Regards 
I have a Primaluna HP Integrated.  I've rolled a bunch of tubes in there.  Contrary to MillerCarbon I find a definite difference in tubes.  I've run the KT120s in mine, and bottom line, I don't any more.  I found them to have a "glare" on the midrange that I could not "tweak" away.  I noticed it on clear, well-recorded vocals where I could hear a "fuzzy" aura around the vocals.  Check around, and you'll see that a lot of users of KT120 report this issue.

I moved to KT150, and that glare went away.  They sound punchy and powerful with none of the glare.  I had those for about 2 years, but I'm now running a new favorite, TungSol 7581A.  If your amp will run them, I'd say give it a try.  They are under $30 each, so not too expensive.  I've been running them about 5 to 6 months now, and my system sounds the best it ever has (although this isn't the only adjustment I've made in that time).  I will soon go back to the KT150s to compare, but I'm loving what these tubes have done.

But, Miller is blathering about his favorite fuse vendor.  I won't argue whether a fuse can make a [slight] difference or not.  When I tried an aftermarket fuse, there was no discernible difference.  That was MY experience.  But, there is absolutely no way that a fuse can have a bigger impact than rolling tubes.  Rolling fuses would be low on my list of improvements to explore first.  Look at Miller's system on AGon, and note that he isn't even running original tubes.  They have a sticker on them from theTubeStore.  They are still KT88s, but I think those are the only tubes that amp can run.

I agree that there are some tweaks that can make it all come together, but IME, you are better to start from a solid foundation before you start tweaking too much.  Adjust your room, tune everything thoroughly, get it to sound good.  Then, tweak if you want.  But, tweaks won't fix a foundational problem, which you may have with the stock KT120s.  You might find improvement with some NOS KT88s or KT120s.  Google "tube rolling" and Line Magnetic 501ia to find what some others have done.  I don't know if you can run the 7581As, but worth a try if you can.  Some different driver tubes and power tubes will make a very noticeable difference in how it all sounds.
Absolutely absurd dismissing that tubes can make a difference while gushing over a fuse. I’ve rolled tubes and I’ve tried Synergistic fuses and other products from SR. All have made a difference but I have to say, a pair of NOS 7308 Mullards from Brent Jessee moved the needle so much more in my preamp than dropping a SR fuse in the same piece of equipment. We shouldn’t be preaching "the only thing that matters is what you hear with your own ears" while dismissing what folks hear with their own ears! This type of cognitive dissonance is really getting old. We are all here to share opinions but self righteous behavior has no place here...it's unhealthy and unkind.
Didn't dismiss. Didn't gush. Merely pointed out, quite correctly, where each is on the spectrum of performance options.

When you have to resort to misrepresenting (ie, lying about) the other fellow you know for sure you have lost.
Another hack:
But, Miller is blathering about his favorite fuse vendor.

Blather? That’ll be the day. Point out the blather. If you can. If not then guess what? You are the one blathering.
I won’t argue whether a fuse can make a [slight] difference or not.

I see. So what will you do, then?
When I tried an aftermarket fuse, there was no discernible difference.

"An" after market fuse? Really? Which one? Sounds to me like you’re trying to call me out without having the integrity to admit you have no idea what you’re talking about, because you’ve never even heard a SR Orange Fuse. Right? More blather.
That was MY experience.

Right. Your experience with.... what? You haven’t said. More blather.
But, there is absolutely no way that a fuse can have a bigger impact than rolling tubes.

Based on... what again? Oh yeah. Your experience with "an" aftermarket fuse! Brilliant!
Rolling fuses would be low on my list of improvements to explore first.

Based on.... your experience with.... ?
Look at Miller’s system on AGon, and note that he isn’t even running original tubes.

OMG! Not even aware tubes do wear out and need to be replaced from time to time! Let me fill you in: even the original manufacturers tubes do indeed wear out and need to be replaced. More learning, less blathering, okay?

They have a sticker on them from theTubeStore.

Thank you, Inspector Clouseau.
They are still KT88s, but I think those are the only tubes that amp can run.

Correct. A dazzling display of blather.
In the big scheme of things though you will hear much more difference changing the fuse inside the amp than changing the tubes.

This is a gush, this is dismissive....this isn’t "correctly pointing out" anything....this is opinion that is dismissive of anyone else’s experiences that they wish to share. 

By the way, I never refer to anyone who lends an opinion as a "hack".  Who does that? Seriously???
Per the OP"

"Can someone help me understand what the specific function each type of tube performs in a power amp?"

This has yet to be answered...

Which pair of small signal tubes drive the KT120's?

I've seen 12ax7's commonly used as drivers, but I've also seen 6SN7's used as drivers in SET amps.

Though driver's can greatly affect the sound I suspect that the OP would be better off rolling the "other" input pair of signal tubes for starters.

Not much on the WWW about this particular model/amp that I came up with.

DeKay
Thanks Dekay for the follow up.  That has yet to be answered and i honestly tries to research this, but struggled to find anything authoritative.  It would be helpful to know. 
Hello @gunners01

I have the Line Magnetic LM-508IA and tubes made a big difference in sound. In fact, power tubes (805 in my case) also made a considerable difference, may be even more than preamp tubes. 

If Im not wrong, you said that your amp has 50 to 60 hours of use. I would burn more the amp as I believe its not enough to judge its performance. In fact, during burning time, one day may sound worse than the day before. I would burn it at least for 300 hours before changing anything. 

Then, if you want to roll tubes, I would start with the preamp ones, wich are cheaper and can give you an idea of the changes. 

By the way, Ive tried changing the original fuse with a HiFi Tuning Supreme one and Ive found an improvement, but not huge. I would start with preamp tubes after 300 hours of burning with out a doubt. 

Good luck!! 

"Can someone help me understand what the specific function each type of tube performs in a power amp?"

This has yet to be answered...


Input stage: 2x 12AX7
Rectifier: 1x 12AU7
Drivers: 2x 6SN7
Power stage: 4x KT120


Thanks plga. I will take your advice.  Much appreciated.  
Also thanks imhififan.  Is there a decoder ring for rectifier?   I think i get the others, but still not sure what role each plays in sound production.  
imhififan979 posts03-25-2020 8:03pm
"Can someone help me understand what the specific function each type of tube performs in a power amp?"

This has yet to be answered...


Input stage: 2x 12AX7
Rectifier: 1x 12AU7
Drivers: 2x 6SN7
Power stage: 4x KT120


I read above the power tubes have some issues also. Nothing I've ever owned used KT120, or 150.  I have always been a 6L6 (lower wattage) 6550, KT88 and 90 user, when it comes to power tubes. I'll bet if they were bios different, the problem might go away. AUTO bios can be an issue..for some valves.

6SN7s have been around a long time, there has to be some great valves out there for that one too. Very good valve. Use to call um double trips,
actually two valves in one.. Can't tell me matching this valve isn't important.

The 12AX and AU7 will cost the least. TONs of options. MATCH the tubes. If there is no way to bios the signal tubes, matching makes a big difference. The quality of the valve, prone to vibration (BIG ISSUE).
(Valve tap with a thin wooden dowel), if you don't have a tester.  An old
school, valve amp guy, showed me that one, the tap test. (Lightly), not a snare drum. Hold the top, one finger, tap the side.
I've  also gotten serious changes with HOW the unit was and is bios,
there is a range say 200-300 (just a number). It can change how the amp sounds A LOT.. The 20-50.00 usd on signal tubes, bios options (if there is any), matching, unit vibrational control (good idea) TWEAKS in the valve world for sure, and dirt cheap..

These, along with, placement, treatment (heaver drapes), controlling the bass usually cleans up EVERYTHING.  just a bunch of stuff  you could do for just a few bucks, in the name of MIDS...You'll get it..

Respectfully The OldHvyMec..


Hope this helps..


Input stage: 2x 12AX7  Preamp tubes in this case, pre to the power amp section. Used to to amplify the signal from the driver tubes (my guess). In the actual preamp.

Rectifier: 1x 12AU7 Converts AC to DC, so the rest of the tubes can do their thing. Starts the whole thing off.

Drivers: 2x 6SN7 usually to drive a higher impedance load, normally into another valve, medium gain tube. Great preamp tube, so Dac, phono stage, guitar pick up, are amplified and handed to the next stage, each stage cleans and boost the signal (normally). In this case to the 12AX7s,
(again a guess) in the power amp section..

Power stage: 4x KT120 final stage, high gain valve. To the load, 

This guy explains a valve amp operation very simply, and thoroughly.
Just great..

How a tube amp works GREAT!!!

Regards
Just read the Uncle Doug's explanation, thanks. 
Gunners, while this forum will give many points of view and numerous prescriptions for getting that midrange that you are looking for it will come down to trial and error. Getting the balance of frequencies in a tube amp to your satisfaction can involve anything in the system. Fuses, power cords, tubes and much more. 
I can speak 6SN7s. I have Chrome domes, Bad boys, GE, Psvane CV181-T11, Shuguang , RCA, Ken Rads. My fav is the Psvane, with the Ken Rad close behind. The Shuguang WE6SN7 had the cleanest midrange presentation but with loss of bass present in the Ken Rads and Psvane. 
It's like cooking to taste. No shortcuts.
Fuses don't make any difference in the sound of any component unless they blow or rot somehow. It's because they're fuses. 
Agree. It definitely does make a difference in the sound of any component when a fuse blows. There ain't any. 
+1 and +100 on more time on Amp. At an average of 2&1/2 hours a month that could take you another two years just to make it to 100 hours.

Did you move your speakers around (what kind)? Please do that first! What's the room like? Power like? Connects like? Sources like? Tube rolling may/may not be the answer.
Wsrrsw 
I’ve perhaps underestimated my hours, but not by much.  On average i may get 6-8 hours a month, but with the current quarantine its maybe 4-5 hours a week.  
Room is large with 14ft ceiling.  Speakers are Harbeth HL5 plus.  Power seems fine and I do use a conditioner, contacts all fine to the. Eat of my knowledge.  All equipment is 3-4 years old. 
Hi gunners01

I have an amp that uses a similar tube compliment. This is what I have done. And it made a Significant Difference! 
Perhaps it can help you in your search towards refining your sound.
 
On the Line Magnetic Website:
https://www.line-magnetic.eu/en/products-line-magnetic-en/integrated-tube-amplifier-line-magnetic-en/lm-501ia-amplificateur-int%C3%A9gr%C3%A9-push-pull-kt120-2x100w-detail

They include this helpful  info:

Tubes Basics              Common Replacements

12AX7                         12AX7EH, ECC83, E83CC, CV4004, ECC803,                                          5751
12AU7                         ECC82, 12AU7EH, 5814, 6189, CV4003

6SN7                           6NP8, 6H8C, 6H8M, 6F8G, CV181, QB65,                                                  ECC32

As others have mentioned, I too have used Brent Jessee as a resource to educate myself on the differences - 

https://www.audiotubes.com/

For the 12AX7/AU7 - I have tried Telefunken, Mullards, Heath, Mazda and Siemens.

Currently I have been very pleased with.. 

2EA. 13D5 /12AU7 Brimar longplates and 1EA. E83CC Siemens 

This combination has the right amount of detail and musicality for me. Increased the depth of the soundstage, fleshed out details in midrange.

Although I find that the Telefunkens are the most detailed, they seem too focused on the upper end, and conversely the Mullards can be too sweet sounding and not capturing the same details in the midrange.

I do not use the 6SN7 Tube, but If I did, I would be inclined to look towards RCA, Westinghouse or GE.

On the Line Magnetic Website they state:

Tubes we choose are.... and Tung-sol KT150

The KT 150s are expensive so perhaps start off rolling the signal and driver tubes, and then move to the KT150s or see if LM would give you a break on a set of replacement KT150s.


Every bit counts, so replacing stock fuses and power chords do help.

I have been happy with Isoclean Audio Grade Fuses

https://www.vhaudio.com/isoclean-fuses.html

Power chords is subjective - cable company has a lending library

https://www.thecableco.com/lending-library


Best of Luck


Good find on the tube info.
TUBES
Input stage: 2x 12AX7
Rectifier: 1x 12AU7
Drivers: 2x 6SN7 (Electro Harmonix)
Power stage: 4x KT150 (Tung-sol)

The tubes that influence the sonics the most are the 12AX7 inputs. They are the preamp and the input gain to the amplifier. This gain stage has a high amount of voltage, thus the sonic signature of different tube brands will be most audible.  
The drivers will have a lesser effect on sound. Their job is to
take the input signal and split it into two identical signals, each 180 degrees out of phase with each other. These signals drive the output tubes. IMO, you can live with the stock 6SN7s for now.
Rolling rectifier tubes most definitely influences the sound.


You have very low hours on your amp. To increase the burnin process you can leave the amp powered up while you are home. Never leave a tube amp unattended.
You only need to have the amp turned on, no components, no music, but the amp must be connected to the speakers.


My amps can take many different output tubes....  that said , it sounds completely different based on the output tube.   The input tube also changes the character of the amps.    It was voiced using EL34 and even the different brands have their own sonic signature ...    currently using JJ EL34 and it is the best sounding of its type I've used.

I run all Aesthetix Eclipse gear: Atlas monos, Janus pre and Romulus DAC/transport. Fully upgraded LP12 with Lyra Kleos (please don't bash the Linn) and Raidho TD2.2's.   My system is pretty much where I want to be.  I rolled tubes in my Aestheix gear for about 18 months before I got what I wanted.  Major impact will come from the transformers and caps (mention above). I noticed this when I upgraded my DAC to the eclipse model.   

The more resolving your system, (obviously) the more dramatic the effect of different tubes. My experience (guided by the fine people at Aesthetix - Jim and Glenn) was the biggest jump in SQ was in the phono preamp. V1 will have the most impact. I tried PSvane, Treasure, Gold Lions, Tele NOS, and finally found it in Amperex ultra low noise12AX7.  Moved the Tele's to V2 and V3 and changed from (6DJ8)6922s to 7308s. For me it was all about low noise floor - which opens up every other sound spectrum IMO.

Changed to Tele 12AX7 NOS and Mullard 7308s in my DAC/CD - which for me really gave it the analog sound I wanted. Based on my experience. I prefer NOS versus new tubes. 

Takeaway:  get everything else where you want it to be first. including your room acoustics!  Identify what you want to improve and check out what Brent Jesse has to offer.  His descriptions are good and will help you identify a possible solution at a given price point. Be careful, with NOS tubes, there are a lot of imposters out there. 

Make it fun.  Enjoy the process.  Good luck