i have used the garage1217 adapters for both 6dj8 and 6sn7 octals... they are well made and bring a whole world of old stock tubes into play for the mhdt tube buffered dacs
only downside is the top cover won’t fit or the tube + adapter will sit high above the top plate line of the unit, so you need to willing to run the dac ’nude’ or topless - that sounds a whole lot sexier than it actually is ... he he he