There was a discussion of this on Head-Fi, either on the main Lyr 3 thread or on the Lyr 3 tube rolling thread. The couple of documented cases there involved rolling in tubes that failed catastrophically. Won't have that problem with the Gilmore, for sure (nothing to roll
) but the experience of many others, including me, is that if you are careful in sticking with high quality new or NOS tubes (I've used so far the Schiit-supplied Tung-Sol, a 1944 NOS Ken-Rad VT-231, and a new Psvane 6SN7-SE), things go well. I love this amp with AFCs or with Ether C Flows, which is what I mainly use with it because the AFCs at at work with a solid-state amp (Neurochrome HP-1).