25v caps instead of 35v caps in ssl 9k psu?

The PSU is on page 5: http://www.studio21.ch/diy/neeno/ssl9k/DIY_9k_Preamp.pdf

Can I use 25v on the 1000uF smoothing caps instead of 35v as stated in the schematic? Maybe peaks when powering up can cause problems?

With a 20-0-20 TX-secondary: no.
20*sqrt(2) - 0.6 is (too much) above 25, so not good.

You could of course use a TX with a lower secondary voltage, but you
need to take care the regulators still have room to work under all mains conditions. Just getting 35V caps will be the least hassle.

[quote author="clintrubber"]20*sqrt(2) - 0.6 [/quote]

Nice formula, didn't know that one.

[quote author="ChrioN"][quote author="clintrubber"]20*sqrt(2) - 0.6 [/quote]

Nice formula, didn't know that one.[/quote]
There are various possibilities for finetuning but in essense it's:
(1) splitting the whole supply in half (equal parts: upper for pos & lower part for the negative supply) and (2) then looking at how much Volts DC you get from one times 20V AC: that's 20V times sqrt(2).
Then (3) subtract a diode-voltage drop and you have an indication for your raw unregulated DC-voltage. This is the voltage that your filtering-caps should be happy with.

Lots of info about this on the net that will describe this all much better etc, but the stuff I wrote are the thoughts behind that formula.