Luxman preamp into Mark Levinson amp?

I am amazed at how the sound stage envelops me. I have heard wide that goes outside the speakers and I have experienced some depth of sound stage but this is new to me. The sound stage is wide and each instrument has a well defined location. What impresses me most is the way the music seems to wrap all around me. It's like I'm in the middle of sound comming from every direction. I think that experience is mostly base extension but the sound stage depth is finominal!

I was looking at Genalex Golden Lion ECC 82 B749 tubes on one web site for $115 as opposed to Genalex Golden Lion ECC 82 B749 on another site for $62. They don't quite look the same but that could be a cosmetic change only. The more expensive source advertizes "Carefully engineered to recreate all attributes of the original vintage tubes". The les expensive source advertises "Price is for a single tube with standard testing" then gives options for "Balanced Triodes (add $2.00 each), High Gain (add $2.00 each), Low Noise & Microphonics (add $4.00 each), and Matching will become available after entering 2 or more tubes". I understand matching sets of tubes but I don't understand what the other options are. The cost difference of the 2 sellers doesn't ballance out when you add the opptions for the $62 source. 62 + 8 is not 115.

I have a couple of questions. First; how do you identify long plate tubes? Second; what do these terms "Ballanced Triodes, High Gain and Low Noise and Microphonics mean relative to the purchase of these tubes?

Thanks in advance

@squirrely , I got mine from Vivatubes, reliable seller with 90 day warranty, they’re selling those now for $49.44 each. Just get a trio or quintet of matched sets, they got both options. If there’s noise, you’ll hear it from your speakers (like loud hiss or humming, etc), microphonics sound like if you put a giant mosquito against the microphone, just imagine that noise is amplified and comes from your speakers. Extremely annoying.

Those double triodes tubes, in this case 12xx7 type, have two sections, and it’s surely preferable to have them matched.
 

@squirrely go to thetubestore (Canadian dealer) and take a look at their Gold Lion 12ax7 tubes. They make long plate and short plate version. You’ll see those two blackish things inside of the bottle in one version are long, and the other version is short. Compare them visually, and you’ll see the difference. Same goes to the NOS stuff, at least as far as I know, and I don’t know everything ;-) 

Thank you Hasmarto. I'll check it out.