[Guy 13]

I did today a tube rolling between Genalex Gold Lion N709-EL84 (Purchased from TC Tubes)
and Electro-Harmonix EL84 (Purchased from Tube Depot)
I also have one 6N15N Russian made, (No make),
originaly supplied with the Decware SE84C+
I only have one because the other one... well roll off the table
and crashed on a ceramic tile, therefore, it did not survive.
The pairs of Genalex and the Electro-Hamonix sound about the same,
very difficult to put into words the sonic difference between the two.
I can hear a difference, but difficult to describe.
The Genalex seems to have more information, not more details,
something more. Bass are about the same,
but I would say that the difference is in the upper mids - lower highs.
I did try the 6N15N Russian made on the left channel, then on the right channel,
the channel with the 6N15N did have more details, especially in the highs,
not a lot, but enough for me to notice.
For me to notice, usually it need to be more, lot more, this seems to be the case.
I should order from Decware another 6N15N (SV83) but I have three pairs of EL84
therefore, I am good for a few years in tube supply - spares.
To improve further more the sound quality of my system,
I would have to spend (Lot) money to get not that much more sound improvement,
therefore, I will keep it like that.
End of tube rolling experiment.

Guy 13

[Wind Chaser]

I had a Decware C and as I recall, there was a consensus among Zen owners that wasn't an EL84 replacement equal to, or better than the stock SV83. However, the stock input tube and rectifier are a different matter, and there were quite a few options, some of them a bit costly but very much worth it. Amperex, Siemens and Bendix come to mind, alas I don't recall the details. It was too long ago, but the Decware Forums is where you might want to do a little research if you want to explore the matter further.

IMO, tube rolling is well worth it and a big part of the joy that comes from owning tube gear, but you have to do a fair bit of research in order to make it pay off. By chaning the tubes you change the character of the component ...and by upgrading the tubes you upgrade the component. I now have a Coincident Dynamo 34SE MK II and I have replaced the stock output tubes to great effect. I also have on order some extremely rare but highly sought after tubes to replace the stock input tubes. Anyway, there are a lot of options available for your Zen.

[Guy 13]

I had a Decware C and as I recall, there was a consensus among Zen owners that wasn't an EL84 replacement equal to, or better than the stock SV83. However, the stock input tube and rectifier are a different matter, and there were quite a few options, some of them a bit costly but very much worth it. Amperex, Siemens and Bendix come to mind, alas I don't recall the details. It was too long ago, but the Decware Forums is where you might want to do a little research if you want to explore the matter further.

IMO, tube rolling is well worth it and a big part of the joy that comes from owning tube gear, but you have to do a fair bit of research in order to make it pay off. By chaning the tubes you change the character of the component ...and by upgrading the tubes you upgrade the component. I now have a Coincident Dynamo 34SE MK II and I have replaced the stock output tubes to great effect. I also have on order some extremely rare but highly sought after tubes to replace the stock input tubes. Anyway, there are a lot of options available for your Zen.

Hi Wind Chaser.
Thanks for your comments.
I am already a members of Decware forum,
at one time I did post quite often, but I don't post often anymore,
I don't like their format, but lots of good information from Decware owners.
I did some tube rolling on the rectifier using Ruby 5Y3, Sovtek 5AR4 and now using
RCA 5U4 and could not tell the difference in sound between all of them.
For the 6922 I've tried a Sylvania JAN 6922, but I am now using an Electro-Hamonix 6922
because it sounds a little better.
By the way, I never rarely pay more than 25 USD for a tube.
If I had the $$$ I would go with the Decware model SE34I.5 
or the Wright Audio Lolita EL34 to get a little more power.

Guy 13