Received a quad of LISSTs for Freya today. Have them installed now. They are stubby ...maybe 2/3rds the height of the new production EH 6SN7s I was running and about the same diameter. Installed without benefit of socket savers to elevate them, they protrude ~1/2" above the top of the Freya case. They are "weighty" for their size. I was a little surprised at how warm they run, even at idle. Right (F & R) gain pair definitely warmer than the left pair. After playing 40 minutes or so it's possible to touch them but not for very long. Sonically any differences from the EH 6SN7s are pretty subtle to my ear...possibly a little less high end extension (i.e., "air") but, then, stage depth seems more evident and better defined. I'm thinking sound quality is like JFET mode but on steroids gain-wise. Amount of gain provided seems comparable to the EHs - maybe slightly more (based on SPL at a given volume knob position). They've only been installed and powered up for 3 hours now and seeing signal for not quite an hour. I expect their character will become more evident with additional time in use.