how can I connect my IPAD 10 to an external NAIM DAC X5 to use lossless audio of apple music ?

Depends on what inputs your DAC has. (Can't find a specific NAIM DAC with that model name, so can't check for inputs)

If it has a USB-C input, you can use a good quality data transfer USB-C cable for that.

If you need to convert it to something else, like optical (Toslink) or s/pdif, then you'll need a USB-C to whatever input your DAC has that supports lossless. Check your DAC's user guide to see which inputs on it support lossless 192Khz audio and you can go from there.

For example:

click here ➜ USB-C to s/pdif adapter 192KHz - Amazon.com

click here ➜ How to get the best out of Apple Music High Resolution Lossless - addictedtoaudio.com

From my understanding and correct me if I’m wrong but you don’t actually need any external DAC to listen to Lossless Audio but to listen to Hi Res Lossless Audio you do need an external DAC as it needs to be connected with a hi res cable through the external DAC to a decent Amp, Hi Res Lossy is not capable to be used via Bluetooth at the moment I believe.

When playing a Lossless or Hi-res Lossless via Apple Music on a Mac, you need a DAC connected via USB that supports the lossless sample rates. Some speakers have built in DAC. I have Audioengine A2+ speakers which support up to 24 bit at 48 kHz.

If you don't have decent speakers and equipment, don't worry about lossless. You will likely not hear a difference.

You should be able to use a good quality USB-C to USB-A cable plugged into the front USB port on the NAIM to get Apple Lossless ALAC audio to it.

https://community.naimaudio.com/t/getting-apple-hi-res-lossless-to-my-nova/17449/96

For example: click here ➜ CableCreation 6 inch USB C Cable Short, USB A to USB C Fast Charging, Braided Type C Data Cord - Amazon.com

Alternatively as mentioned a Toslink or Coaxial S/PDIF cable should also work.

Is this your NAIM DAC that you are trying to connect with