Thanks for responding, guys.
I had read before that the internal memory should be limited to the 250GB. However, while I was reading info on the streamer, I saw this:
"Storage:
SATA SSD: 250GB / 4TB
NVMe SSD: Up to 4TB"
The way it is written, I wondered if there were a way to install a 4TB drive, so that's why I asked about it.
I had noticed the USB connection to DAC in the specs page. I asked my question about other possibilities because I have a tube DAC which lacks USB input. I may need to buy a converter.
If I want the ability to play music from my HD without internet, then I may have to invest in other hardware and/or software in addition to a new streamer.
I'm hoping that Jason will reply with more information.