Tube dampers?

My system consist of Shanling STP 80 and T200 cd player, I have been looking around for tube dampers and I found some o-rings and other types of dampers, dont know which ones will work better for my setup since my El 34 electro harmonix and WE 396A/GE 5670W have a metal type cage around them so I dont know if I will have enough room to play with when it comes to tube dampers. I did look into Brass, O-Ring and Herbies type of dampers however I dont know much about any of them. Any advise?

I've heard about ARC, Herbies, Mapleshade and other vendors, some cheap and some $$$ If you recommend a product please please provide me with a link so I can lookup the information. Not looking to break the bank but do some worthwhile improvements.

Thanks, Robert