Metrum Onyx versus Metrum Pavane

I wanted to see who has moved up from the Metrum Onyx to the Pavane or Adagio and was it worth it?

I currently run the Onyx with Metrum Ambre via I2S.

Let me know who else out there has experience with Metrum in general.

The Metrum DACs do not have a conventional preamp section.  The potentiometer adjusts the reference voltage which in turn affects the voltage output thereby adjusting the amplifier output and the system volume.  Steve Nugent's Empirical Audio DACs do it the same way.

My preamp was custom made by Steve McCormack of SMc Audio from the TLC-1 platform but highly modified and improved so the result is very similar to his VRE-1 preamp.  Mine is set for unity gain while some of the VRE-1s utilize 6dB gain through their Lundahl transformers.  The volume control was an expensive Shallco switch with Audio Note Tantalum resistors.  Steve graciously instructed me how to unwire the Shallco switch so it is out of the circuit but two resistors were needed to replace the switch and I chose to use two very large and expensive Audio Note Silver Tantalum resistors.  I am very happy with the result and the Adagio through the buffer IMO beats the Pavane through the preamp with volume control.
Hi guys, I have read this thread with great interest, as I am looking for a DAC. I have never auditioned any Metrum products nor in fact any R2R DACs. But what I read about the natural timing, flow and micro dynamics certainly strikes a chord here.

I am currently using a relatively modest Innuos ZEN - Naim V1 DAC - Lavardin IT - Zingali Overture 2s, where the DAC is clearly the weakest link. The R2R philosophy mirrors Lavardin capabilities perfectly as far as I can see. I considered Border Patrol DAC, Shiit and some middle of the range Denafrips, but something deters me (for different reasons) from taking a punt and going for any of those. Metrum though looks quite convincing from what I have read so far.  

As my room is far from ideal and I am not an audiophile per se and just prefer listening to the music (no offence to anyone here!) I guess Pavane would be an overkill (tell me if I'm wrong), so I am looking at Onyx.

My main concern is the link to the source, as ZEN has USB output only and with the right application it sounds just stunning. Is the Onyx USB asynchronous? How good is it compared to other inputs? What will I need if the I2S input is clearly superior? I don't want to complicate things by adding another (expensive) box.  

Any thoughts are highly appreciated. And if anyone has the experience with Zingali/Lavardin, any opinions re matching my system would be great! Many thanks. 
A general comment, those looking at high end Metrum DACs should investigate the Sonnet products devised by Cees, the engineer/founder of Metrum before it was sold. I had lots of Metrum products, and the Onyx was my favorite (only used the RCA input via a baby ambre so I can’t comment on USB, sorry!) They have not been responsive of late so I worry about ongoing support (in fact Cees himself is providing “unofficial” support for those products as you will find if you search various forums!) - their stuff is bulletproof in my experience so this post isn’t meant to scare you off buying Metrum, but the Sonnet Morpheus looks like the Adagio in performance for much less money.

Got a sudden opportunity to audition Onyx and Aqua La Voce 3 on Monday. Both were excellent and sounded very similar in many respects. The tempo, articulation were spot on, both excelled in portraying rubato phrasing and sounded quite expressive, nuanced and involving. I was actually surprised how much modern DACs have improved. Bought the Aqua due to its’ slightly more optimistic delivery, and more importantly a better USB input. The fact that it’s modular and probably better supported now, also helped with my choice. Onyx though is a great VFM. Sonnet looks interesting as well. Thanks, roncagg.
I had reached out to Metrum and Anjo said they were working on new products and this was back in January...I haven't heard from him since. I know that there is clearly a sore relationship between Metrum and least that's how Anjo put it. He wasn't happy at all.

Also with Onyx- I would only use the AES or I2S to hook up to streamer. I wonder if your experience would have been better if you could have used either option.