In the late 90's, I tried or owned almost every tube type available in this family. Sold much of it but still own/use certain brands. Recently, I plugged in a pair (unused) of RCA branded Siemens 6dj8's (1968 vintage). After some initial congestion, these tubes showed some impressive traits. Almost as resolving as the SH CCA, more resolving than the SH 6922 (1962 vintage) Vacuum tube valley has them on sale at %15.00 off. Total of $85.00 shipped plus handling fee. A real bargain in this crazily overpriced tube world of late.