Note: All reviews and comments listed in this section are from users who bought their etracer kit at the full price. No advertisement exchange or paid review here.

Mark Walker made a great video clip on building and operating a Sbox12 relay box published on his YouTube channel:

Mr. Masahiro Yonezu is the owner of the blog "Dr. AMP Lab." in Japan. Mr. Yonezu posted a series of articles on etracer. He also posted a lot of test results of various tubes with etracer. Get your Google translate ready because the following links are in Japanese:

「etracer」導入編

「etarcer」製作編①

etracer製作編②

etracer測定編「2A3」

SangBeom is the first etracer user in Korea. He is also an owner of utracer. His comments on utracer were the reasons I initiated the design of etracer. SangBeom's website is in Korean. Google Translate works quite well though.

http://hifimuse.tistory.com/102

Mark Walker currently has 13k+ follower on his Youtube Channel "Blueglow". Mark purchased an etracer kit in September 2018 and he made two video clips covering his building process of etracer. Make sure you check out Mark's Youtube Channel for other vacuum tube audio related video clips.

I've heard about Jean Christophe Morrison, or known as J.C. Morrison for about two decades. JC used to write articles for Sound Practice in the 90s and back then I was the translator for Sound Practice Chinese edition. We never met or connected before JC purchased the etracer kit but I did learned a lot from JC's articles and from his blog. It is an honor for me to get such a positive feedback from JC. 

http://www.labjc.com/?p=4735