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

A non active preamp stage means the preamp stage is passive and just controls volume, there is no gain just attenuation. I have not personally heard the CA-150 so can't comment there.

Just a single dual-ganged pot or a pair of pots (variable rotary resistors). No gain, no noise!

Not heard it but removing the first stage input amplifier does a number of things. It takes out an extra stage of electronics with the idea that simpler is purer. Less crap in the path. You might want to check the input impedence matches the source. Depending on the design it may reduce the "drive" of the amplifier compared to one with an active stage. It is a balancing act between the two.

@sunnyjim - I do not have the CJ, but I have a Naim 5i (Mk II) which also has a passive front end.

Just as another poster pointed out - no active components, just a resistor ladder for volume attenuation and input selector buttons.

When I heard the amp, I was quite taken by the clarity, dynamic performance and expansive image and then over time came to love the very neutral nature of the amp.

I cannot comment on the CJ, but I suspect it would offer similar characteristics. Checkout if it has a resistor ladder for volume attenuation, because they tend to provide better focus to the image (i.e. in my case)

As with any component, the tone may be altered significantly by the cables you choose. I found the NAIM 5i to be very responsive to cable changes.

Unfortunately, I developed my own DIY cables, so I am unable to make any brand/model specific recommendations, but cables that have performed well with my amp include products from KLE Innovations. I also like the look of the cable geometry of Nordost cables. I have heard a couple of their early power cables and they made a noticeable improvements in dynamics, clarity and image.

See if the store will let you demo the amp with your system.

Hope that helps a little - Steve