No reason to be sad Telefunken EC8020 is pretty much unobtanium at this point and even when by some miracle someone sell them NOS price is out of this world. That said 437A is a super tube of nearly the same caliber both EC8020 and 437A are the most impressive marvels of tube engineering ever imo.

20B is still produced by EML and also it's a tube of excellent quality which, assuming a good circuit with correct stable low tolerance heater voltage, boast quite long lifetime for a DHT. Anyway the question is quite ridiculous as it could be applied to any new tube amp made today, since as...

It really does look spectacular

Weird time to be a audio hobbyst... like everyone either just ignores context, misses the point on purpose or fixates on uninportant specs (s/n, thd) and ignores important ones like output impedance, well such is the state of the hobby now I guess. Anyway, if I were to rate W4's sound quality...

Yes, you are certainly right; in most cases, it shouldn't be much of an issue, unless you buy W4 to use it with your 15 ohm tribrid. It simply sounds really bad, much worse than W2. So while 3 ohm OI is not the end of the world, it's a deal breaker for some people—at least it was for me. That's...

That's very nice; I'm happy for you, but none of this has anything to do with the poor damping factor resulting from the interplay of the high output impedance of W4 with low impedance IEMs. Bass will be bad, an undeniable fact that anyone with good ears will notice; some members already did...

Usually yes, but that's only because manufacturers do a lazy job and end up with high output impedance from the 4.4mm output, just like W4. The defense argument is most often shorts protection, but W2 has a 0.7 ohm output; on a 15 ohm iem, that's a damping factor of 20 vs 5 of W4, a difference...

I just learned that this dongle has on 4.4mm output impedance of 3 ohms, woah, that's just... terrible - for a device of this type. You can calculate the damping factor to be a horrific 5 for 15 ohm iems and 7 for 20 ohm, this will modify frequency response of most iems and underdamp the base...

Purely theoretical question but would WA33 with the right adapter take WE437A as driver tube? Putting aside that it's most likely impossible to get 4 of them.

Not sure why would that would be, you can absolutely make a great measuring tube amp if you have a clue what you're doing.

Before Justin drops some more official info on Grand Cayman just a few of my observations: From the choice of tubes we can kind of understand what was the sonic goal here, EML 20B-V4 is very linear and for a DHT we could say super low distortion, ECC99 as a driver is somewhat known for its...

Not him and I didn't test it but just want to say that achieving 98dB S/N and 5Hz to 200KHz out of tube preamp is incredible feat of engineering, then again I would expect nothing less from the Genius man behind Trafomatic Sasa Cokic.

Something that I'm interested in since this amp can also use 6.3V tubes is: 1. Is there enough space to fit some new production 6SN6/6SL7 from Linali? They are considerably larger than typical and its hard to judge from pictures but it looks rough 2. Since 6N6P can be used in place of ECC99...

Sir this amp clearly uses EML 20B-V4, its a completely different tube from 300B.

Wake me up when some measurments drop