Naim Fans

Can I use a Naim 250 and Naim pre without using a Naim PS? I have just drawn a blank on this. So, the question is...can I use a 250 and Naim pre without a flatcap, hicap or supercap or does this not work. Thanx, folks.
No you can not.
I know for sure that my 42.5/110 could run off the 110 power supply or be upgraded by using a Snaps or Hicap. Since the 250 has been around as long or longer than the 110 I would suspect that it would. I bought my system in the early 80's and sold it a couple of years ago here. IMHO, and based on the auditioning I did at the time, you would be better off buying a Hicap and a lesser priced Naim amp for the same total expenditure. That is exactly what I chose to do way back then.
I believe Naim amps and pre-amps work on their own without the power supplies. The power supplies are an upgrade to the pre-amps.

While I'm not familiar with the current crop of Naim components, I know that the 32, 42 and 42.5 which are preamps don't even have power cords. They either use the amplifier power supply or, like you say, the upgrade power supply. I have photos of my old system from when I placed the ad here to sell it. Lindisfarne, just drop me a line if would like me to send them to you. They are about a meg in size. It's easy to zoom in and see how the connections work.
It is my understanding, the smaller sized 180/150/140 type amps have provisions to power certain Naim preamps without a separate outboard power supply.
The larger 250 and mono amps do not have provisions to power a Naim preamp direct and will require a separate power supply.
Try the NAIM forum, those folks will provide you with more details/ideas/opinions than you could ever imagine.
I have a NAP 250, and it most definitely can NOT be run from the preamp.

In the olive series and the black series, these power amps can power a preamp:

90, 140, 150, 180, 200

These power amps can't power a preamp:

250, 300, 500

Even when I was using a 62/90, adding a hicap made a huge difference. It's nice to know you can save some money when you're getting started, but you really should consider a hicap as one of the first upgrades to a Naim system.