Unitilite+nap250dr no sound

My system comprises of a Unitilite connected to NAP 250DR connected to speakers Harbeth 30.2 xd via naim speaker cables.

The speakers are new and today I attempted to set them up.

Because I changed the position of the system in the house, I disconnected the whole system and reassembled and reconnected it elsewhwere.

When the speakers are connected to the NAP there is no sound whatsoever, although there is a humming sound.

When the speakers are connected directly to the Unitilite (the NAP is not connected), they work perfectly with no humming sound (signal ground position at floating)

In addition to the above please note that the last thing I did before disconnecting and reconnecting my system was to upgrade the version of my Unitilite to version v. 4.7.00. Before this upgrading and before disconnecting the system, I had no problems. The Unitilite and Nap worked together just fine. The previous speakers were Harbeth P3esr.

I connect the Unitilite (preamp output) to the NAP input using the dedicated cable.

Has anyone got some advice for a solution to this problem and how to eliminate the humming noise when NAP is connected (when NAP is switched off and Unitilite is still on there is no humming noise, nor there is any noise using just the Unitilite).


The update may have reset the speaker menu settings. Check the speaker menu settings and select EXTERNAL; this switches on the pre-out.

Hi, I suspect Richard is correct that the external amp setting needs to be enabled. Perhaps it was reset to the default internal only during the firmware update.

The ground switch should normally be set to chassis, not floating, unless you have a grounded source (such as a Naim CD player or streamer) connected to an analogue input.

Thank you Richard. Problem easily solved. I feel rather stupid :smile:

Thank you ChrisSU. I have reset the signal ground position to chassis, since the only thing connected to the Unitilite is the Nap. System works just fine now.

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