What is a non-active pre-amp stage?? Are their advantages to this design??

Just to be clear, an active preamp doesn't have to add gain, there is benefit to be had in using the active component/s to present a high impedance to the source and low impedance to the load. DIYers are in a better place to decide which way to go as they are more likely to properly understand the impact of their choices and the electrical characteristics of the equipment connected. 
A passive device needs to be selected carefully because too low an input impedance may overload the source equipment... okay so lets choose a high resistance pot / attenuator. But in the absence of any active components the output impedance of the preamp is the one presented by the pot / attenuator. The output impedance of any preamp in conjunction with cable capacitance creates a low pass filter - with well matched equipment this will be at a higher frequency than we care about in the audio world. However with a passive preamp this may start to creep in to the top end of the audio range.
There are other advantages to active preamps that I could go into but I feel I may have been too technical already.
One architecture isn't necessarily better than the other, but if you don't fully understand the characteristics of your components then you're probably safest going active.

I just re-read the original post and realised I'd forgotten we were talking about an integrated amp (not a passive preamp). You will be able to trust the engineers have taken into account the impedance internally (and so can disregard most of what I just said), the unit has 10k input impedance so that should be fine for most, if not all sources. 

I still think that sometimes it's worth using active components to overcome the limitations of passive ones e.g. if you want minimum noise levels 10k pot has minimum noise of -115dBV, a 500Ω attenuator has minimum noise of 127dBV but will require some active buffering. 

Apologies if I've added more confusion, I should have re-read the original post properly before responding. 

I don't think it's as simple as passive is always better... the rest of the amplifier is active, just no buffers or gain on the input. There always needs to be a reason for the extra components though.

It's fairly easy to produce a very low distortion amplifier with either architecture. As I described, active components can help to minimise the noise floor which for me is important (I'm not talking about hiss or interference) as I like that pitch black background you get from an super low noise amplifier.

I guess we're all looking for our own Holy Grail, but the chances are we won't all agree on what that is. Personally I go for the solution that delivers the most accurate representation of the input signal (just bigger).

Apologies to the OP for going so far off topic... it would have been much more useful if I'd actually heard the amplifier and could just say it's great!