I received the s.e.x 2.1 about 2 weeks ago and finished building on the last weekend.
I have put s.e.x 2.1 + c4s + impedance switch board + power line + badge (basically all except hat, I have a big head haha). Total building time is 5 + 4 + 4 hours (Fri, Sat and Sunday) excluding reading kit manuals a month ahead which I enjoyed a lot. Reading all 3 manuals inside out helped so much when I was building (sending manual earlier was very good idea in both building the kit and keeping me company while I'm waiting for the kits). I just use manuals to double check the part that I'm putting at that point.
As you can guess from my building time, I did not paint my bell and transformers as I like them without paint, but I finished the base with 2 coats of Danish natural oil over 3 days. So it looks just like the manual inside out. =) I might try vinyl cover tapes that other member shows in other thread.
Fortunately, I finished all of them without a major issue. Only thing I had issue was crinkling sound from tubes. I found a solution from the thread easily. It is getting better as time goes by (about 30 hours listening so far) and cleaning tube pins helped a lot. All of my resistors were +-1%, but voltages were -15% for most connections. I'm suspecting this is from tubes. It sounds good as of now so I'm not planning to cook tubes, I'm just going to listen as it better and better. Also, I'm just going to stack some 6dn7 tubes for future failures (so reasonable price haha)
After listening for my s.e.x amp for a week. I can say that this amp sounds so addicting. I have few amps, both tube and solid, that cost more than this amp and I like my S.E.X amp the most at this point. No direct comparison from me, I respected all other amp makers and I believe they have their own strength and weakness which are decided by my own personal taste.
I don't have "golden ears" but sensitive ears so I like my music low volume and still want the all the details. I can never slept with my headphone on, but I fell asleep on my chair with my s.e.x. amp without fatigue. And this sounds specially good with HE-500 on classical/orchestra genre. I always like this can but it did not have spacious sound and detail that I want. Usually, higher watt solid state amp that I have has spacious sound, but did not have enough resolutions. or if other amp has enough resolutions, then it loses the spacious sound. Now, I'm having very good experiences on both.
As I mention before, the main reason I got s.e.x. was I like orthodynamic headphones so much these days, I want some amp that put more watt into the can while it it keeps all sound qualities. But maybe I did not do enough research, it seems very from people to people now. Or I have a bias on my research now since I just want mainline now because Bottlehead is proudly representing the Mainline and it has better sound quality than s.e.x with all the upgrade that I have. I need some good excuses to my wife for justifying to get a mainline haha. Hopefully, a bigger sale in the future =)
I'm considering to upgrade 1.5uf and 0.1uf caps with reasonable priced cap if this helps to improve. I already upgraded a stepped attenuator that I got from ebay and I like it.
Please suggest me some upgrades if cost/performance ratio is good.
Thanks!!!