can i mix a sram chain with dura ace 9 successfully? which model should i get? thnks
Yes. However, the shifting is a little rougher than with Shimano chains. OTOH, you do get the advantage of having the PowerLink. You can also use the SRAM PowerLink on a Shimano chain. I find SRAM chains to be stronger than Shimano chains though. SRAM 9-speed chains (6.9mm) are slightly wider than Shimano 9-speed chains (6.6mm) which accounts for the slightly rougher shifting. Personally, I would recommend the Wippermann-Connex 9-speed chains. They measure 6.5mm, come with a quick-disconnect link (ConneXlink) like the SRAM PowerLink and shift as smooth if not smoother than Shimano chains. They are however slightly pricier. For Shimano 9-speed drivetrains, the following SRAM and Wippermann chains will work:
SRAM
PC-951 - Standard steel, no nickel-plating, bulged sideplates for improved shifting and durability, hardened pins
PC-971 - Nickel-plated bulged outer plates, no nickel-plating on chamfered inner plates, hardened pins
PC-99 - Nickel-plated inner and outer plates, Cross Step reinforced and hardened pins, my "best-buy" SRAM recommendation for budget chains
PC-99HP - Nickel-plated inner and outer plates, hardened hollow pins (lighter)
PC-991 - Nickel-plated chamfered inner and bulged outer plates for improved shifting and durability, hardened pins
PC-991HP - Nickel-plated chamfered inner and bulged outer plates for improved shifting, hardened hollow pins (lighter), my personal SRAM recommendation for high-end
PC-991CS - Nickel-plated chamfered inner and bulged outer plates for improved shifting and durability, Cross Step reinforced and hardened pins
Wippermann-Connex
900 - Unplated steel
904 - Nickel plated outer-link, unplated inner
908 - Full nickel plated, my "best-buy" recommendation if on a budget
909 - "Gold" brass-plated for that extra bling
9C{1,2** - Color-painted in a variety of colours, 9C1 is blue amd 9C2 is red... other colours are available I think and can also be custom-ordered with special colours, fully nickel-plated, same quality as 908
910 - "Champagne" tint for classy-bling, fully nickel-plated, same quality as 908
911 - Lightweight version of the 908, hollow-pins, slotted sideplates, full-nickel plating, my personal recommendation for high-end drivetrains, about 50% more expensive than 908
920 - Teflon coated version of the 908, recommended for extremely corrosive environments such as riding near saltwater or for those who don't like to regularly lube/clean their chains
9X1 - Stainlesss steel, extra strong, anti-rust, expensive
9TR - Titanium-Roller version of the 911, very expensive (~$300), hollow-pins, slotted sideplate, comes draped like a necklace inside a jewelry case
Note that there are other chainmakers such as KMC. I have had the best experiences with SRAM and Wippermann though.