NOS KT 88s or GE 6550s

I am currently running a quad of Gold Lion KT 88s in my Conrad Johnson LPS 70 power amp. At considerable expense I can switch to NOS KT 88s or GE 6550s. Would this be a sideways move or a real improvement over the current production Gold Lions ? Would appreciate the advice/comments of CJ or ARC power amp owners who have made the switch. Unfortunately a demo in my system is not possible.
Many thanks in advance.
As far as comparing the Gold Lion to the NOS tubes, I have no idea what the difference would be. Going from KT88's to 6550's would probably be a big change. There are so many factors involved that its almost impossible to guess at something like this. If it was my call to make and I couldn't somehow do a demo, I wouldn't take a chance; espically if the cost is very high. CJ is a great company and if the tubes in your amp are stock, I would trust that the tubes are a good match. They wouldn't pick a tube that didn't sound good.

Now that I think about it, are the KT88's in your amp stock? The reason I ask is that I don't recall CJ ever using the KT88. I'm not up on their current models, though. The CJ amps I have owned in the past either had EL34's or 6550's.

You may want to give The Cable Company a call. They have a huge lending library of cables, accessories and components. I'm not sure if they lend out tubes, as well, but they have a very big selection. I've used them many times in the past and I find them to be very honest and trustworthy. Even if they don't lend tubes, they may be able to give you some useful info.
Many thanks for your response. The CJ came 6 years ago with the stock Winged C 6550s. These were replaced with the KT88s based on advice from fellow Agoners and others. I have am happy with the sonics but have always been curious about the improvement that NOS tubes can provide vis a vis current production tubes. You are right that this is highly subjective and any opinion is valid only in the context of a system/room/musical preferences and priorities.
Would still love to share the experience of Agoners who have switched to NOS for their CJ or ARC power amps.
I do not own either amp but I do own an Octave V70SE integrated. Mine came with SED KT88's and I also ordered a quad of SED winged C 6550. The SED 6550 is a very linear sounding tube where the KT88 is a little warmer. Next I got a quad of the GL KT88 re-issues. The GL's fall somewhere between the SED 6550 and KT88's. Later I scored a quad of Tung Sol 6550 solid black plates. Wow what a difference. More like the SED EL34 - magical mid range ever so slightly rolled off highs and not much in the bass dept or power when compared to the SED or GL. The TS 6550 solid black and grey plate have the bass and the power the EL34's lack. Later I picked up a quad of Gec KT88's. Very linear but with a tighter low end and more 'sparkly' for the highs.

That being said I do not own or have even heard the GE 6550. So to summarize I have to say the SED 6550 - Gec KT88 and GL KT88 are all more 'solid state' sounding where the SED KT88 and Tung Sol solid black and grey plates are more 'tubey' sounding. Now if you like the Gec KT88 sound and want even more of the same try the EAT KT88's. Another KT88 that I have is a KR Audio branded Tesla. A hair more of the Gec KT88 but not quite an EAT. So if you prefer the SED 6550's the Gec KT88 is a big step up. Sorry I can't comment on the GE's but I'm trying to give you an idea of the differences between the SED 6550 - GL KT88 and Gec KT88's.

Last to me all tubes sound good but there are sonic differences between types and manufacturers. So types like 6550 or KT88 can not be lumped into a particular sound category. Another Great tube I have is the Ei KT90 type 2.
Sunnyboy, I have heard both the GE 6550's and the GL KT88's. IMO, the GE's are some of the very best tubes ever made. If you like midrange magic and the ability to drop down in the bass dept, then you will LOVE these. The GL KT88's are almost veiled in comparison. The SED 6550's are very very good and are a fairly close second to the GE's in the 6550 range. Only problem is the GE's are usually very hard to find in decent condition.
I say go with the GE's if your amp can use them.
Contact Ed at C/J and find out if you can put KT-120's in that amp.
I did send a mail to CJ in early July regd the KT-120s. No response. I should have followed up. In any case I got a quad of GL KT 88s as a replacement for the Winged C 6550s.
I think you just convinced me! I am trying to work out some sort of refund deal with the Singapore dealer for the NOS GE 6550s, in case things dont work out.Are there major differences between the GE and Jan 6550A , both NOS ?
Many thanks
KT120s continue to rack up the cred...I stuck a set of them in a newer Jolida 502p that wasn't designed for them (I did check with Jolida and they insisted the extra heater burden was non issue) and stood back in case the amp was gonna hasn't and it's been many months. I'd like to try a set of GL kt88s (I like the way they look...lame but true) but somehow I can't justify pulling the 120s since they sound so good. Your results may vary of course, but I still have never heard of anybody's amp transformer melting from the extra juice demand of 120s...I think it's a myth, but what the hell do I know?
Well, it make take a few years before damage happens. This of course depends how over built the heater winding of the transformer is. Obviously 4 KT-120's would be less of a burden than 8 etc.
Just as points of reference regarding heater current draw:

GE 6550A: 1.6A
Genalex KT88 (1974 vintage): 1.6A
Ei KT90: 1.6A
SED =C= 6550C and KT88: 1.65A
Tung-Sol KT120: 1.8A
Original Tung-Sol 6550: 1.8A

conrad-johnson has given its blessing to using the KT120 from at least the Premier 11A onward for its amplifier product line.

Whether there is any damage down the road is doubtful IMO, but only time will tell. I do know that many c-j owners are using the KT120 with no reported difficulties so far. Personally, I prefer the Tung-Sol reissue 6550 to the KT120, but that's a matter of taste.

I've also used the GE 6550A and it's an excellent sounding tube, and few match it, again IMO. Whether you think it's worth the extra cost is unfortunately something only you can ultimately decide.
I've been told that the transformer would get into trouble sooner than later if the KT120s were incompatible somehow...but my informal research results remain: Happy KT120 users in the thousands, reported transformer deaths 0. It will be a sad day when all these overworked transformers give it up. I do like the Tung Sol 6550s that came with my amp and I swap 'em in when I'm bored or have a need to burn my fingers, and I also have a set of Sovtek KT88s that sound fine but lack the groovy gold lettering of the Gold Lions, so there's that. I understand the gold lettering makes them sound 13% better than otherwise.
Pradeep, I haven't heard the NOS JAN 6550A...were these GE's as well and just Joint Army/Navy or ?? I do own a matched quad set of GE 6550's that are like new, and once my SED 6550 C's give up the ghost will replace them with the GE's. You have to be VERY careful that the GE's you will be receiving will still be good. I have heard several horror stories about supposed NOS GE's going up in smoke. I had this happen on my amp when I first acquired it, however, I knew that the tubes were very old and it was a matter of time before ..poof. Happened almost immediately after I acquired the amp...luckily no other damage except to the tube itself.
I don't know what all the fascination is about with the GE 6550's. I always remember them to be just okay and had issues with them in Dynaco Mklll's so i never used them. Later versions of the tube had major issues with high plate voltages or high bias currents hence the Dynaco issues. For that matter so did the Genelex KT-88 as they would routinely arc and blow the fuse. I much preferred the Philips Sylvania 6550 that Audio Research used for many years. An excellent tube and much more robust than the GE IMO. The Sylvania was a smaller tube than the GE.
The Singapore dealer (Well Audio Lab) tells me there is no difference between the GE and Jan 6550s.

So much of it comes down to the circuit we're using the tube in and our personal preferences. Some is just blind luck in terms of getting a good or bad batch. I have both the ST-shaped and the straight-sided Philips Sylvania 6550's and they are very nice tubes, I agree. I prefer the ST-shaped but again, that's just my opinion.
Hifigeek1, perhaps if you could listen to a good amp using the GE6550's you would see what the fascination is all about.
I have heard them in an Audio Research D-76A as well as a D-79. They sound great but the newer versions of that tube are just not very reliable.
Hifigeek1, what newer versions are you talking about? The GE 6550 tubes that I have used and heard were all very good sounding and quite reliable. If you are talking about another brand, well that's a different situation.
For a few years Richardson was making 6550's using GE's tube machines that they had purchased. Tube looked the same but that's where the comparison ended. They were miserable.
Hifigeek1, I trust the Richardson 6550's weren't GE branded, or??
They were not branded GE. They looked identical but they obviously got the recipe wrong. I think they scrapped the idea. I think the reason no one is making tubes in the U.S. is more about osha and the nasty chemicals that are used in the process of making a tube than anything else.