hello there. new on this forum

I would like to solicit an opinion or perhaps advices i recently bought ASL AV20 (6L6) tube monoblocks paired them with tube preamp.i e-mailed ASL's creator and asked what type of 6l6 power tubes that these monoblocks can only accept and he said all types and i can
even use el34 to them. i"m quite a lover of el34.

did anyone try to do so? is it ok to do that? i'm not well versed in electronics so your advise will be highly appreciated.

thanks and regards.