@lpretiring - I can answer this for you, since I had this exact email exchange with Vlad about the very same thing, as it is my concern as well.
With the stock tubes (the two pairs of sub-miniature 5977 tubes, which incidentally have a pair installed on each 9-pin adapter) the max voltage is only 1v. If using a pair of 6N1P (or other tubes in the 6922 family) the gain is 6db, so you will max out at 2v.
With the stock tubes (the two pairs of sub-miniature 5977 tubes, which incidentally have a pair installed on each 9-pin adapter) the max voltage is only 1v. If using a pair of 6N1P (or other tubes in the 6922 family) the gain is 6db, so you will max out at 2v.