I understand the reluctance to recommend specific tubes as the selection is a matter of personal taste. But I think that rule could be relaxed a little when I indicate that I like your description of one tube to put in my device, what do you have that has similar characteristics to go in another position in the same device. The obvious comparison is choosing speakers and if someone asks which ones are best there is no right answer as the choice is personal. But if someone says I like this speaker and that speaker, what have you got that's similar, a sales advisor could probably make a suggestion or two.