I have a Bifrost and Lyr 2 ordered, and while waiting for it to get here I have ordered a couple of sets of tubes to go with it.  I had a tube headphone amp that I used briefly, so I am pretty nw to this.   My question is this:  How long do I need to use a tube to get a feel for how it will...

I am about to buy a Lyr 2.  I will eventually get better tubes, but for now, should I go with the 6BZ7 or the LISST tubes that are an option when ordering it?

I have a bit of a weird situation, so bear with me.   I am currently going through a divorce and my stuff is 1600 miles away.  In that stuff is a Darkvoice tube amp and a pair of LCD-2s.   Right now I have a pair of HD598SE, and will probably be getting another, different set of headphones...