Cube Audio Nenuphar Single Driver Speaker (10 inch) TQWT Enclosure

Too bad Pass Labs can't develop another source for static induction transistor devices.

   I suspect they could have their own made, but it wouldn't be cheap. It sounds like that is what Aries Cerat did. This summer EnjoyTheMusic had a short new item on Aries Cerat and their new Ianus series of electronics.
www.enjoythemusic.com/news/0720/

Aries Cerat Ianus Series amplifiers is a showcase of the company's unique TriodeFet technology. After years of developing and refining their technologies, they are proud to introduce the TriodeFet technology, and a Series of amplifiers that implements this truly innovative technology. This technology is neither a hybrid topology (in the usual sense of a tube-driving solid-state stage type), nor a solid-state driving tube kind of stage. TriodeFet is a new way of using hollow and solid-state devices. The concept is to have a low voltage / high current active device, which had the linearity of a triode, and at same time would be able to source enough current to drive low impedance loads directly.

The TriodeFet, can be seen as a three terminal active element, just like a MOSFET or a triode. The company's breakthrough is that its transfer curves are identical of a true high quality triode, with the only differentiator from a true triode is that, the Y-axis (current) is in scaled in Amperes and not mA. What this means, is that you can design circuits that were never before possible either by using tubes or transistors. This new active element can be used to develop simple, very linear circuits, which are stable down to very low impedances, while the TriodeFet's inherent linearity is making the use of the problematic negative feedback redundant. New models within the Ianus Series include the Geminae (€110,000) Class A amplifier that produces 130 Watts @ 8 Ohm. Aries Cerat's Essentia (€39,000) is the little brother that produces 40 Watts @ 8 Ohms.

@rwpollock Perhaps you’re just suggesting that pass finds a new manufacturer for the SIT devices? The first run was custom made by Semisouth for Pass Labs (hence the Pass label on the transistors), but they have since closed the factory.

Some interesting discussion here with input from Nelson: https://www.diyaudio.com/forums/pass-labs/222098-semisouth-goes-dodo.html

Correct. It's not my field, but I wouldn't be surprised if there aren't chip foundries that will do custom work and small runs. Not cheap, but perhaps Pass could buy a passel from Aries Cerat or have their supplier make a different version.

Maybe he will given the success of the sit amps. I've heard they're starting to get low on their supply and the sit3 was only possible because the parts have been so reliable. Previously, those transistors had been held in reserve for replacement service. 

Funny that Nelson said this in 2012 (from the above thread on diyaudio):  "I predict that long before I run out of SITs there will be some new, perhaps more interesting devices to play with."

“New models within the Ianus Series include the Geminae (€110,000) Class A amplifier that produces 130 Watts @ 8 Ohm. Aries Cerat’s Essentia (€39,000) is the little brother that produces 40 Watts @ 8 Ohms”.

That makes the FW SIT-1 a bargain. Given the FW SIT-1 has 2 watts/ch at 1% distortion, yet it sounds more like 50 watts/ch. I have 9ft ceilings and my dedicated listening room that has no back wall to speak of is open to a decent size kitchen/eating area (shaped like an “L” close to 600 sqft) and I’m never wanting for high volume.

I also want to report that the FW has opened up nicely and has a beautiful mid bass response. I also found that like the Ayon Audio Odin, the FW SIT-1 benefits greatly by adding SR ECTs near the on/off switch, binding posts, the male IEC connector and on top of the transformer. I had these on my Ayon Audio S-5 also and they eliminate high frequency grunge that provides a multitude of benefits in the recreation of music.