Different Tubes and general purpose?

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.