Can I connect multiple sources to an external DAC

I have a Bluesound Node that's connected to a Topping D90SE DAC through USB. The Bluesound recognises the DAC, which can be selected. 

I have two CD players connected to the DAC, one with Optical and the other with Coax. 

The desired input can be selected with the Topping's remote.
 

Equipment connected to my Gustard X26 PRO dac:

- Node via USB

- Digital FM tuner via coax

- Jay's cdt2-mk3 CD transport via I2s and also via XLR for overly bright albums. 

So yes, that's what good dacs are for, multiple connectivity.

My Pure Audio Lotus DAC5 has 7 inputs. 2 coax, 2 optical, 1 USB, 1 11S/DSD, and 1 AES/EBU. Selection is by remote. That would seem to cover just about everything anyone would need. Oh and also it's a great DAC. It did more for my set up than Denafrips Pontus, MHTD Orchid or the Topping D90SE.

I have a simple solution to your problem and it will cost you $26. I was always running into the same problem as I have multiple Sony mega storage CD units I use as transport.

Just a couple weeks ago I decided I am NOT buying anymore DAC units. In addition, I am not going to spend a ton of money on a DAC that has a couple extra optical ports. It would seem to me there should be a whole row of them on ANY half decent unit. 

But anyway... Here you go. Hit Amazon, look up a LINKFOR digital toslink optical 4x1 switch. Btw.. LINKFOR is the brand new, that is not a typo..

So easy it is stupid! There are 4 optical inputs and (amazingly) 1 output. Just plug up anything you need to run to your external DAC , use the remote to turn this little unit on, select which port you need and wow- problem solved.   I was able to free up a couple of DACS that I wasted money on for some other projects. I am running 3 CD decks and a streamer thru this thing and it works perfectly!!! Gee, all for $26 bucks and I love it. http://LiNKFOR Digital Toslink Optical 4x1 Switch with 3ft Optical

All Denafrips DACs accept multiple inputs.

The Ares accepts USB, optical, co-ax, and I2S. The Pontus II and Venus II add BNC co-ax and AES/EBU. The Terminators add RJ45 I2S

hope that helps