where can you get good step attenuators ?

I am looking into making a passive preamp ,who makes good step attenuators and which is best SMD resistors or standard ones?

how about 24-step Ladder Type VR kits with knob and 96 1% Vishay Dale RN60D resistor
The TKD stepped attenuator is very good. Percy Audio has them. Steve McCormack uses it in his upgrade of the TLC-1 passive preamp.
Electronic Visionary Systems at: www.tweakaudio.com hand makes great attenuators. I have used a pair for about a year on my system. Check out the website or do a search here for "EVS attenuators" to find out more. Check them out.
I have always voted with fellow users of the artisan crafted EVS Ultimate Attenuators for $350 retail, by Ric Schultz of tweakaudio.com. They attach directly onto the amplifier RCA input jacks so that you eliminate one potential interconnect purchase. There is a model for either tube or transistor amplifier. Most appropriate for single source system where you play either CD's, or vinyl records. You must have an amplifier whose sound you prefer, because you will hear all the performance your amplifier is capable of delivering, without any alteration.
Look at these sites:

For DACT: http://www.diycable.com
Also has transformer-based passive kit.

For Goldpoint: http://www.goldpt.com/index.html
The best source is Michael Percy (www.percyaudio.com) that have Shalco attenuaters stereo or mono whichever you'll prefere assembled or kits at smaller than half price of EVS and performance near or even better.
They're being used in mega-priced Blue Circle preamps.