According to the Limetree Bridge Mk1 User Manual, it supports DSD, but it coverts it to PCM - I assume transcode, not DoP encapsulation - when you use it’s digital output. It’s stated in the “Product Description” section in User manual;
When sent over the digital outs, the DSD data are automatically converted into high-resolution PCM data so that owners of oder DACs can also enjoy high-res media of all kinds.
So, if you continue to use the Lindemann Limetree, theres no way to get native DSD into your Elgar+ DAC.
In order to get DSD natively into your Elgar+, you’d need to use FireWire (IEEEE 1394) as Pete explained - which I believe necessitates a legacy dCS Transport - or more practically, a dCS Network Bridge or Vivaldi Upsampler, and use their SDIF-2 output into the Elgar+
One other 3rd party option is an exD USB-to-SDIF-2 converter - made by an outfit in Hong Kong - but they’re hard to come by these days.
Good luck! 