I tried them they work, sound like shit. Best way I can explain it if I remember right is the amp lost some distortion but the sound was "woofy". Also the dynamics of the amp when sustaining a chord was not as "tight" The good of them is there seemed to be more clean headroom.
I rolled 5 different power tubes in the amp before deciding on some old RCA 6L6s in it, those sounded best to me and are still in the Custom.
I also tried
- KT66 Pretty good, might have gone this way if I were only playing blues with less gain
- EL34s They were new Mullards, not bad but not as nasty as the 6L6s
- KT88s see above
- KT77 ......Much like the EL34s
- 6L6 I liked the cleans and the total overdriven sound