Naim Fans

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.

Muzikat,

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.