My new classic nap160+nac12s Need help

Sounds like RFI.  Often this is down to a few possible things; first check that the speaker cables aren't acting like aerials.  Make sure you are using the recommended speaker cabling to the correct minimum length and good connections - check how cables run. Second, check your source.  Naim get it's signal earth reference at the source, which once upon a time was usually an LP12 turntable with arm and cartridge, and in more recent times, a Naim CD player. However, faint radio pickup can also be a sign of an amp in need of servicing...

There's lots on this phenomenon posted in the past on here, so search on some old threads for more info.

This is very likely RFI being picked up by moving coil phono boards. Try reorganising the cables or perhaps moving the amp. You can have things added to stop the RFI, but it reduces sound quality. 

When we lived in London and I had a 32.5/250, we could hear taxi drivers' conversations over the stereo when a taxi pulled up outside. Then there was Russian radio in the evenings....

I get this "radio" breakthrough with MM, my radio is normally the very powerful Radio Russia transmitter.  A friend gets the same with MC.  We both use the same fix - route the phono leads through a single clip on ferrite core,  I have one pass & that works for me,  my buddy has a ferrite on each lead & with a double pass (loop).  Its simple & cheap & it works 

The speakers cable is Chord Apex 3M each side and originally terminated. It is a very heavy shielded cable...

The only source connected now is a NAD Dac working wifi.

anyway i think to replace the MC card with a line one. Ill use a TT with a phono stage.

I am not sure the OP has a turn table. Clearly one has to be careful with MM - I suffered with my own radio break through once with MM - indeed multiple loops around a ferrite ring on the phono internconnect between cartridge and phono amp fixed it - but we are down at micro volts..

If there is no phono board or connected phono leads - or the radio break through occurs on any input at any volume setting - its more than likely to do with speaker cable, health of amp or suspect signal ground - or a combination of all three

Simon

EDIT OP confirmed does have phono cards - yes try removing and see if situation improves - but it sounds like happening on multiple inputs? Also heavy shielding itself doesn't necessarily remove radio breakthrough issues - as the induced RF current can flow through the ground or earth - and depending on environment and circuitry still cause issues with intermodulation/detection and breakthrough

Hungryhalibut posted:. 

When we lived in London and I had a 32.5/250, we could hear taxi drivers' conversations over the stereo when a taxi pulled up outside. 

I had the same issues with a 32.5/250 and Taxis! although not in London

When I lived in Longsight, I got very loud RF breakthrough from a minicab company a couple doors down. And on occasional evenings I picked up Radio Moscow-but sadly only in mono. Since my only source at that time was a turntable, I did not have the option of trying using it without the MC boards. 

If you have a t/t and need the boards left in place, then I found out that it was possible to greatly effect the amplitude of the RF breakthrough by simply moving the turntables (unshielded) ground wire around. A ferrite core may be equally as effective if it is the ground wire at fault. 

Experimenting with coiling, uncoiling and moving around speaker cables can sometimes also do the trick..but this is more of a problem in active systems where multiple runs of speaker wires are used.