Using passive pre with Nait XS

I'd either use the NAIT XS as it is, without the passive pre, or else look for a power amp that has been designed to work with a passive pre-amp.  My experience of using Naim amps with passive pre-amps is that while you may make some gain in transparency, you lose much more in energy, drive and overall engagement. Hardly a surprise as perhaps more than most other amp makers, Naim power amps have been designed to be used with a corresponding active Naim pre-amp.

p.s. For all  that, Naim do use a passive pre-amp in their most affordable integrated amplifier, the NAIT 5i - that's because at that price level it gives the best cost/performance, and the power amp section, while based on usual Naim practice, has an extra primary gain stage added which effectively allows the passive pre section to work at its best.

Would I be right in thinking you've already bought the passive preamp and the Harbeth SHL5.

Finding a poweramp to match both of these may be difficult; I certainly know of no way to predict how well a particular amp will work based solely on specifications (and I actually designed and built a poweramp to drive Spendor SP2s! from a passive pre).  It's possible to say that an amp with a lower input impedance is unlikely to sound good (but even that is by no means certain and depends on the type of input structure).

It's certainly worth trying the XS used as an integrated amp (in the way it was designed to function).  Using the LDR preamp into the XS's AV input (with the AV bypass switch set to ON) may work well, but there's no way to know without trying it.

Well, if you have the Nait, and the passive preamp is already ordered, then you can do a simple comparison and let us all know the answer! I suspect it will in part depend on whether your personal preference is for what the Naim preamp does to produce the 'Naim sound', and that is something no-one else can answer.

Thanks for the responses. Am I right when I say the input sensitivity is 130mv and input impedance is 47k ohms? This is the amp section specs for the XS, correct? These numbers are great for a passive if that's the case. I know numbers aren't that important for the sound but in my case it is to make it work at least. I may try this 

No, didn't buy the XS yes but I did the pre. 

Thanks for the responses. Am I right when I say the input sensitivity is 130mv and input impedance is 47k ohms? This is the amp section specs for the XS, correct? These numbers are great for a passive if that's the case. I know numbers aren't that important for the sound but in my case it is to make it work at least. I may try this

No, didn't buy the XS yes but I did the pre.

dubidubi posted:

Thanks for the responses. Am I right when I say the input sensitivity is 130mv and input impedance is 47k ohms? This is the amp section specs for the XS, correct? These numbers are great for a passive if that's the case. I know numbers aren't that important for the sound but in my case it is to make it work at least. I may try this

No, didn't buy the XS yes but I did the pre.

130mV is the preamp sensitivity. The spec doesn't seem to state the power amp sensitivity, but given that it quotes the volume controlled output as 775mV and that is a common standard, I guess that will be the power amp input supensitivity. Impedance not quoted -a guess might be that it would be the same as Naim's srand-alone power amps, but for definitive answers you'd need to ask Naim. 

If you want to use it just as a power amp, why not buy a stand-alone one? (Or is it just that a particularly good deal is available?)

Innocent Bystander posted:

dubidubi posted:

Thanks for the responses. Am I right when I say the input sensitivity is 130mv and input impedance is 47k ohms? This is the amp section specs for the XS, correct? These numbers are great for a passive if that's the case. I know numbers aren't that important for the sound but in my case it is to make it work at least. I may try this

No, didn't buy the XS yes but I did the pre.

130mV is the preamp sensitivity. The spec doesn't seem to state the power amp sensitivity, but given that it quotes the volume controlled output as 775mV and that is a common standard, I guess that will be the power amp input supensitivity. Impedance not quoted -a guess might be that it would be the same as Naim's srand-alone power amps, but for definitive answers you'd need to ask Naim. 

If you want to use it just as a power amp, why not buy a stand-alone one? (Or is it just that a particularly good deal is available?)

Outputs from digital sources may be 1or 2V, so I would expect a passive preamp output to go from zero up to approaching that level, which could drive a power amp direct - but if you're saying the output is only up to around 130mV meaning you need 130mV or therabouts amp sensitivity for your passive preamp to feed, then it seems you'd have to use a preamp input on the Nait, making the passive rather pointless.

Nait AV input
130mV RMS for max power output at max volume setting.
7V RMS overload margin (i.e. at -35dB volume setting and lower)
47kΩ impedance

Digital sources (Red Book standard)
2V RMS max output at +18dB
250mV RMS at reference level (equivalent to 0VU on an analogue system)