[audioxpert777]

Hi all
I have not been here for quite awhile and am needing some help understanding about changing tubes in a CD player. Does it really make a big difference or just a little. I am referring to the 6SN7 specifically. Purchasing an Oppo  with tube mod etc. Thanks all for your input, Larry

 

[Happy Camper]

Each series made by a manufacturer will have a "house" sound. Different applications (military, space, etc.) might have tweaks  in spec that make a tube sound differently in audio gear.
 
The value of those differences is subjective to the listener. IMO, they can make a noticeable difference. There is a thread for 6sn7 tubrolling.
 
http://www.head-fi.org/forum/thread/479031/6sn7-tube-addicts
 
http://www.head-fi.org/forum/thread/117677/the-reference-6sn7-thread