Upgrade or Downgrade Changing Bel Canto 3.7 For New Denafrips Pontus 15th?

I own the Pontus 15th and I can tell you it is an absolute steal.Denafrips really served us a gem of a deal. I upgraded my system from the Aune Twins (Sc9 Dac & Sc1 clock) if you want to stay under $1,400 this is the setup to consider and yes it sounds much better than an Aries II which i also own (the twins have a very detailed but smooth R2R like signature). All that being said when I understood Denafrips was offering a step up (Venus 12th) at a 50% off discount I pulled the trigger for the Pontus,you cannot go wrong here...grab one now before Denfrips cannot afford to cover the tariff hit which they are doing now

I believe you have a fundamental problem with what you are trying to do.  The Onkyo C5 CD/SACD does not have an IS2 output unless you have had it modified? The S/PDIF outputs (optical/Toslink, and Coax) do not output a native DSD signal. 

Am I missing something?

@ucrazykid 

You are right in what you say but my SACD playback limitations are confusing.
The Onkyo is only present in my system as it will play SACDs as a 'native' SACD player outputting an already decrypted digital signal to the Bel Canto through toslink. My main CD player however is the PS Audio Perfectwave but it is just a CD/SACD transport, not a player.
My wish is to use the PS Audio Perfectwave for all SACD playback too, but the SACD transport signal is only playable through an I2S connection (Sony Copy Protection limitation). The Bel Canto 3.7 doesn't have an I2S input, hence potential move to the Pontus 15th. that has this input (and whose pinouts can be tuned to connect to the PS Audio unit) as there is no standard pin configuration for I2S connections!
The new setup would then be PS Audio Perfectwave playing both CD and SACD connected via I2S connection to the Pontus 15th. The Pontus 15th then connected to my Kratos amplifier through balanced XLR. So you are not wrong with your comments about the Onkyo.

Ah! I see. So they Onkyo won’t be needed once you have the PS feeding a DAC from its I2S output.  Got it. 

Why not a PS Audio Direct stream Mk I. They're selling reconditioned ones for $1600.