DINs should be used into the Naim (Supernait) amp, and RCA to DIN cables do exist.
Probably want the Supernait in an AV Bypass mode (consult your manual) to pair with your Audio Visual setup (driving main two speakers ‘as a power amp’).
Sure; valve phono stage between Turntable and amp.
Most Phono stages I have seen alter low level Vinyl output to be like a standard ‘Line Level’ as found on most hifi kit… (and hence now connects to ANY input that isn’t Phono); again benefits may come from using RCA to DIN Cable here from the phono stage to the amp input… (the turntable connected to the phono stage using your best RCA cables).
When you switch Aux (-whereever the phono stage input is connected) over to the AV Bypass input (AV on my Nait amp, but requires a switch around rear being changed-again- read YOUR manual), the volume/preamp duty on the Supernait are bypassed and the Supernait acts as a dedicated power amp to improve the AV processors sound (“a lot” in most cases).
I suppose I’ve made no mention of the NDX5 and HiCap…
I fully understand why capable enthusiasts like feedback from forum goers…
to inform, I’m new here and barely know the Naim products.
DIN inputs will offer advantages, and buying some DIN to RCA may help with that (certainly on an XS series NAIT).
The Supernaits are better internally for workong with RCAs directly, so, if you already have nice hookups; do continue to use, please…
Some might question your present ‘amp splitter’ situation - and this moght need some clarity for forum users to be informed of any advantage/disadvantage to THAT; I’d certainly encourage using an AV Bypass mode instead…(guessing is the same thing)…
regarding “am I missing anything?”; hard call- stuff like feeding 2channel PCM digital out from the TV to the Supernaits inbuilt DAC, perhaps? (simple/easy “high quality” ‘TV sound’); I know the AVR is high quality and multichannel,… but depends on family members’ I suppose… (and setup may have amp controlling seperate voxes that do the streaming TV stuff, and hence need be in use… (or you could take a digital OUT from the amp, and reroute to the digital in on the Supernait, so ALL sources (digital) into the Pioneer AVR get pushed on to the two channel DAC in the Supernait. (will require PCM and not ‘multichannel’ sound sources).
TL: DR
Supernait connected to AV amp using ‘AV Bypass’ setting on the Supernait.
Phononstage into any standard line level input on the Supernait too.
RCAs as usual, except where possible, upgrade to DINs (RCA to DIN cables exist; check pin configuration suits direction of signal; eg some DINs are input AND output plugs and cables can do either based on configuration).
DINs are not essential, but nor is AV Bypass.
Both shouldimprove sound quality.