Your best bet is to put the better tubes in the back as they affect 85% of the sound by accounts that I've heard. I have 4 NOS Russian mil-spec tubes in the front four and a pair of early 70's Siemens E88CC's in the rear. Granted my CDP (Musical Fidelity A3CD) doesn't have a great deal of slam to begin with it is my opinion that if you are looking for slam that you should look beyond these tubes as well. Having said that, these tubes do sound much better than the stock ones. Good luck.
What tubes are being used with Sonic Frontiers L1
My cd player is the Meridian 508.24 and I'm interested in the most musical sound with slam I can get. I'd like to know what others are using. Presently I have 4 Bugle Boys in the front and two original factory tubes in the back.