Usb or Optical

That SMSL is rare streamer/dac with optical input, so optical solution really inexpensive for you. Whether usb or optical superior will have to be determined by you.

Auxinput one of the few who get it that usb or optical directly off motherboards not optimal. If there is one thing I'd like to get across to people it would be this. I find it inexcusable so many servers don't have optimized usb built in. Benjamin at Mojo Audio  was one the few  who understood this with his Deja Vu server, too bad not available any more.

Optical in same boat, only the Small Green Computer Sonicorbiter I9 addresses this.

Expect to spend more money and have more complex setup with most servers since they don't address above issue. One should ask themselves why all these usb renderers, decrapifiers, streamers exist? Because they're doing the job server should be doing.

I'm also curious about these rare dacs with optical input, interesting you prefer usb, at least so far. Is this due to your entire chain or quality of usb vs optical input on dac? I'd bet on usb input being superior as technology has been around much longer and reclockiing etc. SOP these days.

First thing is to determine best input on dac, generally going to be usb with most. Once you determine this, you then optimize the compatible output on server or streamer. Optimization means both inputs and outputs optimized, otherwise not truly optimized. For usb out that means JCAT, Pink Faun usb card or external usb renderer. I'll repeat, very few servers with optimized usb. For example, Innuous Zen certainly seems popular, Innuous also makes Innuous PhoenixUSB, seems Innuous is very aware of their server's usb liabilities.

Just to throw a monkey wrench into this. Another option that hasn't been mentioned is a second ethernet port on server, this way you avoid the lousy motherboard issues with usb or optical. Simplifies network as you can do server>FMC>streamer/usb renderer or streamer dac. I use this configuration with Sonore OpticalRendu as streamer/renderer. You can also do server>whatever ethernet devices you like. This also eliminates the need for a network switch and the added cabling necessary with it.

When speaking of optical here, I'm not talking about Toslink.

People need to keep this conversation on track. Toslink has no bearing in streaming, toslink is inferior optical connection between two digital devices, generally cd transport. This thread is steaming oriented, we're talking about network optical. Network optical does not add jitter, op has rare optical input streamer dac. If his usb sounds better its because either optical out on server inferior or optical input on streamer dac inferior or combo of both. I'd guess usb on streamer dac being superior as this technology has been around long enough so  most dac manufacturers  allocate most resources here. I've observed usb usually outperforms I2S inputs on most dacs, theoretically I2S should be superior as native protocol within dacs.