I am using my Bartok 2.0 with Denafrips Terra World Clock with excellent result. Terra can output a 44.1K and 48K signal at the same time.

Absolutely.

I may be able to share some experience as I have once owned all three, despite I sold my Tak and WE subsequently (but repurchased WE just now). 1. Elrog (non-Mo): Amazing all rounder with the best high low dynamics and the most HiFi sound. Not very 'tuby' in sound and having unbelievable...

Agreed. Frankly speaking the new WE300B is very good with sweet mid and better imaging than Elrog. The Elrog is not a typical 300B but an all round performer, though not sounds as "tuby" as WE.

Fostex HP-V8 with Telefunken CCa, GEC KT88 and Elrog 300B.

Yes it was a mystery but I am not able to retrieve anything on the recall due to safety consideration. So far it operates perfectly without overheating on the transformers and runs smoothly without any hiccup. BTW there was a very rare fully operational one sold in Yahoo Japan at a price of...

Fostex HP-V8 with Telefunken CCa, GEC KT88 and Elrog 300B.

A quad of matched WE300B freshly from the plant with date code 2413. What a breeze both visually and sound with the NAGRA PL-P and 300P.

A quad of matched WE300B freshly from the plant with date code 2413. What a breeze both visually and sound with the NAGRA PL-P and 300P.

Nagra 300P with Nagra PL-P

Nagra 300P with Nagra PL-P.

Some streamlining on my head-fi system and luckily the sound quality remains superb.

Nagra 300P with 4 Elrog 300B tubes.

Here comes my latest addition of Nagra 300P, driven by 4 Elrog 300B in my setup.

Exactly, it makes quite a big difference on imaging and overall smoothness of sound surprisingly.