You will need to use one of the preamp outputs on whichever power supply you use to power the NAC282 (Hicap or supercap). You should slug the
Lead though - iirc Naim used to fit a 100r resistor to the DIN plug on their own sub lead.
You will need to connect to one of the 4 pin outputs on your hicap, or on your Supercap if you get one of those. You need to make sure it is the right sort of lead. This is because it will be longer than usual so may need a resistor. The alternative is to use a high level signal from the back of your speakers to the sub. On the other hand you may find that with the better amplifier you don’t need a sub at all.
Could I know where I could buy the cable to connect my HiCap DR (connected to Naim 282 preamplifier) to my Subwoofer SVS SB13-Ultra (with XLR or RCA inputs) ?
The length of the cable must be approximately 2 meters.
The Naim sub lead I’m not sure is still available to buy new - you could try asking your Naim dealer. It was available in 5 or 10m length. You might find one available somewhere secondhand though. Any lead you use will need to be very low in capacitance and may also need to be slugged with a resistor to ensure the Hicap remains stable (it was never designed to drive long cables).