Metrum Onyx versus Metrum Pavane

In general, I like the coaxial input the least of all.  I have had good luck with USB, AES/EBU, and I2S.  The AES/EBU seems to have a little more drive and both I2S and AES/EBU seem just a tiny bit more natural-sounding to me.  Coaxial was a bit thin-sounding in comparison, although they were all pretty good-sounding.

Ok thanks Mitch for the information, much appreciated.

@mrotino 
I forgot to add, if you like your sound now, I would probably not spend the money on the Ambre.  However, the Ambre is a very capable endpoint and in my system has compared favorably with the much more expensive SOtM triad three piece ultra endpoint with which I am limited to using USB.  You will not go wrong purchasing the Ambre but with things like that I would not anticipate the move to be a "game changer."

@mitch2  what would be a game changer in terms of a streamer?

I do not have wide enough experience to answer your question but I will tell you what I can.  I went from an $8K CD player to a Mojo Audio Mac mini server then to the Antipodes DX.  I have had Antipodes upgrade the DX twice and then added an outboard end point so I run Ethernet directly to the DX and then Ethernet from the DX to the endpoint (currently the Metrum Ambre or SOtM triad since I own both) and then either USB (when using the SOtM endpoint) or AES/EBU or I2S (when using the Ambre) into my Metrum DAC.  Switching from the internal Roon endpoint in the DX to the external endpoint (either Ambre or SOtM) was a bigger change IMO than going from Ambre to SOtM.  This current set-up easily tops the $8K CD player and is the best front-end I have had (I do not use vinyl).

Removing my preamp and adding the Adagio DAC-direct actually made some difference in resolution, even though my other DAC is the very good Pavane L3.  I want to try adding the preamp back in so I received instructions as to how to remove the volume control from the preamp circuit by installing two resistors - resulting in a unity gain buffer.  Volume will be controlled by the Adagio while the SMc preamp will maybe add a little special sauce. I purchased two (expensive!) Audio Note 2W Silver Tantalum resistors to perform the bypass so I am excited to hear the result.