RCA 6SN7GT for Bada-PH12
This is a Sticky under the Amplifier reviews section
The RCA grey glass 6sn7 (drarthurwells refers to them as black glass) make a great combo as a front (input) tube. The Raytheon T plates as the rear power tubes are sharp and dynamic with great bass. Those who find they are lacking bass on the AKG 701 need to try the RCA grey glass as the input tube. It also smooths out the midrange on the 701 which I have found to sound both shrill and lack bass fullness with the wrong tubes. If your do not have the Raytheons (make sure they are the T plate as Art advises) you can try new EH 6sn7, NOS Sylvania GTA short bottles or the stock Shuguangs but make sure the RCA gray glass is in the input position.
Right now I have the Ken-Rad VT-231 as input w/the recommended Raytheons as drivers. I figured: if the K701 don't render bass with the Ken-Rad, then there just ain't no bass to be had, no how. Maybe I'm unduly biased by the chock-full-'o-bass Ultrasone Prolines, but I did not perceive--even with the Ken-Rad driver--that the K701 bass improved dramatically, or even that perceptibly.
An RCA 6SN7GT grey glass lies at the ready, however. God willing, I'll put it in next Monday, when it's safe not to blow the MosFETs. : )