What does AV Bypass actually do? (Using a Qute as a source with my Nait XS2)

As I understand it, AV bypass allows you to take an input from an AV amp and use your Naim power amp to drive the front two speakers in a 2.1, 5.1 or 7.1 home cinema system. The "bypass" means bypassing the preamp to allow volume control of all the speakers from the AV amp. If you aren't planning on plugging your AV amp into your Qute or Nait XS you don't need to worry yourself.

Simple: AV Bypass, (when the AV input is set in Bypass mode), bypasses the amps volume control.

This allows the line level output to be sent to the power amp directly, with the volume being controlled by the AV surround processor.

If you have a UnitiQute, a NAIT XS and an AV processor, you have a couple of options regarding the connection of the AV processor:

• the power amp section of the NAIT XS is better than that of the UnitiQute
• the preamp section of the UnitiQute is more flexible as regards app-based control than that of the NAIT XS
• unity-gain on the UnitiQute and AV bypass on the NAIT XS accomplish the same thing as regards AV volume, but different ends as regards the manner in which this is done (true preamp bypass on the NAIT XS, versus fixed-gain on the UnitiQute)
• you may wish to use the UnitiQute into the AV bypass on the NAIT XS, bypassing the preamp section of the NAIT XS altogether, and plug the AV processor into the UnitiQute.

Thanks for the quick replies.

I do not have an AV processor - Just the UnitiQute into the Nait XS2.  I have RCAs from the pre-amp out into the Nait AV input.  It's just a question of engaging the by-pass switch on the back of the Nait.

If it is just the volume control that is bypassed then it would seem to make sense to use bypass and still have the advantage of the Nait's pre and power amp sections.

That's still not exactly right.  AV Bypass bypasses the pre-amp, which by definition means it bypasses the volume control.  If you use AV bypass then your XS is simply a power-amp and the volume level is set by the unit connected via the AV input when AV bypass is switched on - the other unit has to have a pre-amp output, as it appears your UQ does, because it is the pre-amp in this arrangement.

If the other unit can be used as a "source" like a CD player for example, then the AV question is irrelevant and any normal input will do.

Judge posted:

That's still not exactly right.  AV Bypass bypasses the pre-amp, which by definition means it bypasses the volume control.  If you use AV bypass then your XS is simply a power-amp and the volume level is set by the unit connected via the AV input when AV bypass is switched on - the other unit has to have a pre-amp output, as it appears your UQ does, because it is the pre-amp in this arrangement.

If the other unit can be used as a "source" like a CD player for example, then the AV question is irrelevant and any normal input will do.

I'm not sure that is right, from the manual...

Note: The AV Bypass feature must be used with care. It
bypasses the Nait XS 2 volume control leaving any signal
connected to the av input to be passed to the speakers at
full volume.

I believe that it still uses the preamp to buffer the input signal.

See the spec at
http://www.naimaudio.com/hifi-products/nait-xs-2
It doesn't give a separate input sensitivity of 750mV for the AV input - which is about the input sensitivity of Naim power amps...
Gain = 29dB (approx x30)
70W / 8Ω ~ 23.5V
23.5V / 30 = 780mV.

ALL the inputs are specified to have 130mV sensitivity, ergo the AV input is via the pre amp.

So with the AV switch engaged the pre-amp is switched to a fixed gain - is that what buffering means?

I use the AV bypass on my XS2 to integrate it with the surround sound, it works well.